[[quoteright:330:[[Film/CityOfEmber http://static.tvtropes.org/pmwiki/pub/images/ember-cave_196.jpg]]]]
[[caption-width-right:330:That first step's a doozy.]]

->''"All the roots hang down, swing from town to town\\
They are marching around down under your boots\\
all the trucks unload beyond the gopher holes\\
There's a world going on underground."''
-->-- '''Music/TomWaits''', "Underground" - ''Music/{{Swordfishtrombones}}''

A very short distance beneath our feet, there dwell fantastic beings, societies and terrors.

Those who live Beneath the Earth are often exiles from the World Above. They fled either to create a new home for themselves, or to harbor their grudge for revenge (depending on how well they did). Alternately, they may have fled to escape [[TheEndOfTheWorldAsWeKnowIt The End Of Their World As They Knew It.]] If they had better technology or more resources, they might have built an ElaborateUndergroundBase or even an UndergroundCity; but if they don't they have to make do with simple caves and tunnels.

The {{urban| Fantasy}} area version of this trope is a remarkably livable sewer system. Sewers are surprisingly clean and warm, relatively speaking, with good lighting and electricity access. Maintenance crews never stumble across the living quarters, nor do power companies realize the drain. (Sewer Dwellers don't pay electricity bills.) New York has an especially crowded sewer system.

Go a few kilometers deeper, and the Earth's crust is filled with spacious caverns. The really lucky underground dwellers will have a LostWorld thing going, with tropical flora and fauna in abundance (although occasionally with monsters like [[EverythingsBetterWithDinosaurs dinosaurs]]).

Not so lucky ones (who often want revenge on whoever forced them to live here) get gloom, fungus (often of [[FungusHumongous incredible size]] and [[MushroomMan possibly sentient]]) and lava [[ConvectionSchmonvection (which tends to be somehow survivable)]]. Often based on the "Morlocks" in Creator/HGWells' book ''Literature/TheTimeMachine''. Particularly well-to-do ones will build an UndergroundCity instead.

Often found side-by-side in with the UndergroundLevel and AbsurdlySpaciousSewer. In mythology, folklore, and fantasy, this is typically where you'll find TheUnderworld. (Or [[{{Hell}} that other place.]]) In ScienceFiction and pulp settings, this will often be home to the MoleMen, as well as dinosaurs in any eventual lost worlds. In fantasy, expect instead to find [[OurDwarvesAreAllTheSame dwarves]], [[OurGoblinsAreDifferent goblins]] and [[OurElvesAreBetter dark elves]] making their homes down here. The KingInTheMountain can also be found here, resting until his hour of need comes again. When there's a whole hidden social system living underground, in secret but fairly regular contact with the mundane surface population, that's a WainscotSociety. See also MouseWorld, which is basically this but on a smaller scale, and DugTooDeep.



!! Urban

[[folder:Anime and Manga]]
* ''Manga/GetterRobo'': The Dinosaur Empire, where evolved dinosaurs were forced to hide underground since Earth was being bathed by a type of cosmic radiation -- the Getter rays -- that was killing them.
* ''Manga/SgtFrog'' gives us "[[Anime/MobileSuitGundam Side 6]]", and underground city which functions as home and refuge for all alien immigrants on Earth. Apart from being underground, it looks ''exactly'' like any other street in Tokyo, with Expies of known locations like Akihabara.
* ''Anime/KotetsuJeeg'': The Yamatai Kingdom were a subterranean civilization, too. They had attempted conquering Japan in ancients times but they were defeated and fled underground. BigBad Queen Himika definitely harbored a grudge and longed for revenge.
* ''Anime/MazingerZ'' and ''Anime/GreatMazinger'': Not surprisingly, ''Anime/MazingerZ'' was the one introduced this trope in HumongousMecha anime. The Mykene were a civilization lived and thrived in the Greek island of Bardos millennia ago, using [[HumongousMecha mechanical giants]] [[ChestBlaster blast fire from their chests]] to protecting their land from invaders. An earthquake destroyed their island and forced them to seek shelter underground. They lived below Earth for millennia, building their cities in networks of subterranean tunnels and caverns and grafting their bodies into HumongousMecha to survive. Unlike fromn other examples from this trope they did not strictly harbored a grudge against humans... but they did not like them, nonetheless.
* In ''Anime/TengenToppaGurrenLagann'', all of humanity has been forced to live underground by the Spiral King Lordgenome. The inhabitants of Jiha village, at least, have been down there so long they no longer believe the surface exists.
* The city of Lux in ''Anime/{{Texhnolyze}}'' is underground. The ancestors of the inhabitants had been banished there.
* In ''{{Manga/Uzumaki}}'', there is an UndergroundCity [[spoiler:located beneath the town of Kurozu-cho that seems to be the source of the spiral curse]].
* ''Manga/MadeInAbyss'' has, well, [[DeathWorld the Abyss]]. Despite the name, it is for the most part well illuminated because of the fluorescent mists that pervade it. The farther down someone travels, the more elaborate its contents become, with upside-down forests, enormous plants, flying serpents, and buried cities existing in the depths. People risk death to retrieve the incredibly valuable artifacts found on the lower Layers, although past a certain point, the MaybeMagicMaybeMundane Curse of the Abyss means that [[YouCantGoHomeAgain return becomes fatal]].

[[folder:Comic Books]]
* There was a group called "The Morlocks" in ''Comicbook/XMen'' who lived in the sewers. They were mutants who ''couldn't'' pass for normal humans. Originally the Morlocks chose to have their physical appearance altered by Masque as a sign that they had rejected the surface world. Their name is a ShoutOut to the subterranean race from Creator/HGWells's ''Literature/TheTimeMachine.''
* Much deeper than the Morlocks lies Subterrannea, inhabited by yellow-skinned, weak-willed humanoids and ruled by various humans who've gone there over the centuries -- most notably the Mole Man, a ComicBook/FantasticFour villain. Also from Marvel is the Lava Men from ''ComicBook/TheAvengers''. Also lots of [[{{Kaiju}} giant monsters]] (because hey, giant monsters gotta live someplace). Supposedly, most of these beings were genetically engineered ages ago by the [[Comicbook/TheEternals Deviants,]] ''another'' subterranean race who were themselves genetically engineered by [[SufficientlyAdvancedAliens Celestials.]]
* The ''{{Series/CSI NY}}'' comic "Bloody Murder" brings Mac and company into contact with a group of sewer dwellers under New York City.
* ''ComicBook/JudgeDredd'': Mega-City One was built right on top of the old cities of the eastern United States, which have since become the Undercity, an inhospitable area now housing feral mutants and various other nasties. It's so dangerous that it's sometimes chosen as an alternative to exile in the Cursed Earth by Judges who take the Long Walk.

[[folder: Fan Works]]
* In ''Fanfic/TheLionKingAdventures'' story, ''The Lost World'', Simba, Nala and Haiba discover an underground world populated with [[spoiler: [[EverythingsBetterWithDinosaurs dinosaurs]] and backwards [[TheWildWest Wild West]] lions.]]
* Or, beneath the surface of the Flying Island of Tipaan in ''Fanfic/TheKeysStandAlone: The Soft World''. Most of the Svenjaya have to live in the Svenjaya tunnels. The tunnels play a key role in the Tipaan chapters.

* The sewer-dwelling hoboes in the movie ''Film/{{CHUD}}'' mutated into the titular Cannibalistic Humanoid Underground Dwellers.
* In ''Film/DemolitionMan'', the anarchist/rebel types led by Dennis Leary's character live in tunnels beneath the city of San Angeles.
* All the way back to ''Film/{{Metropolis}}''. The rich live in a bright shiny modern city and the workers live in dreary underground apartments accessed by huge elevators crammed full of people at the end of each shift.
* From the Franchise/StarWarsExpandedUniverse, though not seen in the movies, there are Coruscant and [[VideoGame/KnightsOfTheOldRepublic Taris]], and any other city-planets or very large cities that get mentioned. The rich live at the tops of skyscrapers, the poor live much lower down in those skyscrapers, in slums crushed under the weight of and with the sun blocked out by said skyscrapers. And then there are the outcasts, who live either in caves, sub-basements, or the AbsurdlySpaciousSewer systems required by such large populations. Franchise/StarWars is ''much'' more of a [[CrapsackWorld crapsack 'verse]] than the movies show.
** The lower levels of the giant forests of Kashyyyk, referred to as a 'layered deathtrap' with 7 levels. The Wookies only live at the top level, with level 4 or lower very seldomly ventured to.
* ''{{Film/Marebito}}'': A man obsessed with fear finds his way into a warped underground labyrinth world and rescues a feral girl who turns out to be a vampire.
* ''Franchise/TheMatrix''. Zion, Humanity's last civilization free of the Matrix is located underground, powered by geothermal energy.
* ''Film/TheLordOfTheRings''. Moria, the subterranean dwelling of the Longbeards Dwarf clan under the Misty Mountains.
* ''Film/BeneathThePlanetOfTheApes'' had one that combined urban and caverns. The humans who escaped the fall of civilization thousands of years earlier retreated to buried New York City and due to living next to a giant nuclear warhead,they became mutant, telepathic humans by the time Taylor and the rest arrived.
* ''WesternAnimation/AnAmericanTail'':
** The cat gang.
** The exiled tribe of Native American mice in the third film (though this also crosses over with caverns, being that there is a system of small mouse-sized caves beneath the New York subway system in which the tribe dwells).

* ''Literature/TheDresdenFiles'' has Undertown, an area under Chicago full of mildly-radioactive supernatural beasties, and [[spoiler: the endless EldritchAbomination prison extending under Demonreach]].
* ''Literature/{{Neverwhere}}'' by Creator/NeilGaiman (based on the LiveActionTV miniseries written by him, see below).
* The plot of the book ''Literature/TheRelic'' centers around a monster living in the tunnels beneath a museum, and its sequel ''Literature/{{Reliquary}}'' had mutants dwelling in the deepest parts of New York's sewers.
* In Neal Shusterman's book ''Downsiders'' there is a whole community of people who live under New York City in [[spoiler: what is really a large extension of the subway system, built in secret]].
* Suggested in the novel ''Literature/TheWarOfTheWorlds'', as the artilleryman briefly involves the hero in a plan to form an underground resistance movement against the Martians based in the London sewers (which, he says, would be swept clean by the rain once they've fallen into disuse), using tunnels connected to cellars throughout the city. Nothing, besides a single half-dug trench, actually comes of his plan. [[SarcasmMode To be fair]], he'd only had a week to dig, [[BrilliantButLazy and one can't always work]].
* Interesting example in ''Literature/TheChroniclesOfNarnia'', where there is a "Deep Realm" beneath the surface of the ([[FlatWorld flat]]) earth ruled by the Lady of the Green Kirtle, but it turns out that many of the enchanted slaves there are actually from an even deeper realm called Bism, where gemstones are alive. Once roused from their enchantment, they find the so-called Deep Realm uncomfortably close to the sky...
* The fairies in the ''Literature/ArtemisFowl'' series fled underground in order to hide from humans, and while not exactly thrilled to be there, they've made quite a society nonetheless.
* Khazad-dûm, in ''Literature/TheLordOfTheRings'' is beneath ''Middle-Earth''.
* The ''Literature/{{Tunnels}}'' series takes place almost entirely underground. Starting with the discovery of an underground city called the Colony, the protagonists move progressively deeper with each book.
* In the fourth book in the [[Literature/LandOfOz Oz series]], ''Dorothy and the Wizard in Oz'', Dorothy is reunited with the Wizard, and they make a journey through various realms beneath the Earth, before coming back to the surface in Oz.
* In MikhailAhmanov's ''Ash'', humanity's only extrasolar colony is nuked in a WarOfEarthlyAggression, resulting in survivors hiding in an underground city built just prior to the destruction. Other survivors live in a base under the ocean. Earth forces have no idea anyone survived but continue to nuke the surface. The underground survivors are building nukes to retaliate against the enemy base.
* In ''Literature/{{Shadowmarch}}'' series, Funderlings designed and built entire town beneath the Southmarch castle, as well as labyrinth of caverns and tunnels beneath it. Similar subsurface Funderling town exist beneath Syan, and there are probably other beneath various cities through Eion.
* The novel ''Dark Cities Underground'' posits that this trope exists as modern-day fiction's retelling of the myth of Osiris.
* ''Literature/DeltoraQuest'': Lief, Barda and Jasmine discover the descendants of the Pirrans living on underground islands beneath Deltora.
* The Darke Halls in ''Literature/SeptimusHeap'' are a huge, subterranean cavern that forms a Darke realm.
* In ''Literature/TheIronTeeth'' web serial, the protagonist Blacknail was born in tunnels beneath a human city. His tribe used to live there for generations. A large monster filled network of caves called the Deep has also been mentioned, but only briefly explored. Small insects called Harvesters live there and build vast mushroom farms.
* Literature/TheUnderlandChronicles is all about this trope. More than 90 percent of the books take place in an underground world beneath New York called the Underland.
* ''Literature/TheWeirdstoneOfBrisingamen'''s [[OurGoblinsAreDifferent svart-alfar]] live beneath the earth, and the protagonists have to spend some time spelunking through abandoned (human) mine workings as well.
* In ''Literature/WhispersUnderGround'' Peter Grant discovers an underground colony hidden amongst the Tube networks, the sewers and the illegal teenage raves of London.
* In E. M. Forster's story "Literature/TheMachineStops", humanity lives in underground complexes, as the surface air is cold and poisonous. [[spoiler:Or at least that's the official story.]]
* Common wartime workers in Creator/PhilipKDick's ''The Penultimate Truth'' live and work in underground "ant tanks" while armed robots fight on a fatally irradiated surface. One of them, Nicholas St. James, is sent to the surface and learns that [[spoiler: the war has been over for years and its engineers have kept them below surface in order to take the land for themselves]].
* Creator/RolandSmith's ''Beneath'' sees the protagonists winding up in a colony of people under New York City... whose leader is plotting to one day return to the surface and take over.

[[folder:Live-Action TV]]
* ''Series/{{Beauty and the Beast|1987}}'' featured "the World Below", an elaborately gothic underground colony secretly constructed long ago and connected with the sewers and subways of New York.
* Fruity, Matt and Chaka in MTV's ''WesternAnimation/{{Downtown}}'' venture into the subway tunnels in New York so Matt can tag the trains; while they wander around, they talk about all the crazy inhabitants they've heard tell of. Suggestions include: survivalists, mole people, giant snakes, and transit cops who stage fights.
* The [[Series/{{Neverwhere}} miniseries]] and novel ''Literature/{{Neverwhere}}'' (both by Creator/NeilGaiman) mainly take place in an elaborate underground society beneath the streets of London. There's definite magic in the setting, though, and some hints that the lower chunks of the system aren't really connected to the "real" world.
* In the ''Series/{{Bones}}'' episode, "The Woman in the Tunnel," Brennan and Booth investigate the murder of a woman who was doing a documentary about an underground society under Washington D.C. Brennan finds the society fascinating.
-->'''Dr. Brennan''': Every society has its bottom-dwellers, and every society fears its bottom-dwellers, because they are a symbol of what happens in that society if you fail.
* ''Series/DoctorWho'':
** The underground shelter in the story ''The Enemy of the World''.
** Also the Undercity of New New York in "Gridlock".
* The Compass Killer on ''Series/{{CSI NY}}'' was tracked to his hiding place in a forgotten underground apartment beneath a park in Queens, and pursued through adjoining storm drains and sewer tunnels.
* ''{{Series/Angel}}'' has Angel and company stumbling onto a community of sewer-dwelling kids after Jasmine takes over the outside world. Not to mention the Buffyverse has all the demons, vampires, ect, that live down there.
* On ''Series/{{The 100}}'' the Mountain Men live in [[UndergroundCity an enormous underground bunker]] inside Mount Weather, as the radiation levels on the surface are lethal for them.

[[folder:Tabletop Games]]
* ''TabletopGame/{{Shadowrun}}'':
** The Seattle Underground, a real-world complex of abandoned and buried buildings from the 19th century, has been colonized by orks and trolls as a cross between this trope and an ethnic neighborhood.
** Thousands of years earlier in the same Verse, artificial underground cities called kaers provided shelter for ''Earthdawn'''s inhabitants during the time of the Horrors.
* Skullport, located under the city of Waterdeep, is an example of this trope from the ''TabletopGame/ForgottenRealms''.
* Several ''TabletopGame/OldWorldOfDarkness'' games incorporate this trope. ''TabletopGame/VampireTheMasquerade'' has Nosferatu warrens, while ''TabletopGame/WerewolfTheApocalypse'' has Black Spiral Dancer hives.
* ''Underworld'', a relatively obscure RPG, has a setting and flavor similar to that of ''Literature/{{Neverwhere}}'', but set under New York City instead of London.

[[folder:Video Games]]
* ''VideoGame/CityOfHeroes'':
** The titular city has an impressively large, intricate, cavernous, and heavily-populated sewer system. If heading down there, expect zombies, evil cultists, devil-worshippers, Nazis (untill they got {{RetCon}}ned out, anyway) and cyborgs. If you head deeper into the Abandoned Sewer System, you'd better bring friends, since it's virtually covered with interdimensional mutants, hostile aliens, demons, ghosts, and the occasional tentacled superdimensional [[MonsterOfTheWeek monster-of-the-week]].
** The "lost city of Oranbega", archaic and arcane ruins teeming with the Circle of Thorns and their summoned behemoths which lies beneath even the sewers.
* ''VideoGame/{{Metro2033}}'' features the post-apocalyptic variant, with a small civilization of humans clashing in the depths of the Moscow underground railway after a devastating global nuclear war.
* In ''VideoGame/FinalFantasyXII'', after TheEmpire invades Rabanastre, all of the city's inhabitants are forced to live in the underground tunnels formerly used for storage of goods and merchandise except for the extremely wealthy people.
* The Locust Horde in ''VideoGame/GearsOfWar'' lives underground. The day that they began their war against humanity is referred to as "Emergence Day" due to them bursting up out of the ground.
* ''VideoGame/FallenLondon'' takes place in a version of Victorian London that was transported under the earth as part of three terms of a DealWithTheDevil on the part of Queen Victoria to save Prince Albert's life. Its spinoff, ''VideoGame/SunlessSea'', explores the Unterzee, the vast underground ocean that surrounds London.
* Rock Bottom and the Mermalair from ''VideoGame/SpongebobSquarepantsBattleForBikiniBottom''.
* The subterranean world Derek Badger of ''VideoGame/{{Poacher}}'' finds himself trapped in does not only have towering cities inhabited by disembodied spirits, but also beaches and forests, and even a jungle.
* ''VideoGame/ProjectEden'' takes place almost entirely under a futuristic megacity. It's not all sewers, either - a lot of the game area once was inhabited, or part of massive maintenance systems and factories. Some neutral characters still live down there... along with a lot of hostile ones.
* ''Subterranean Animism'', the eleventh ''VideoGame/{{Touhou}}'' game, gave us the underground city Former Hell. It's the place where [[ExactlyWhatItSaysOnTheTin Hell used to be]], but now it serves as the city where {{Youkai}} who are hated by other Youkais because of their dangerous abilities live.
* The [[MoleMen Tunnelers]] in ''VideoGame/FalloutNewVegas: Lonesome Road'' resulted from the mutation of the Divide's residents who took shelter underground during the [[TheEndOfTheWorldAsWeKnowIt Great War]]. [[spoiler: [[NiceJobBreakingItHero The second nuclear catastrophe, triggered by the Courier, released them to the surface]].]]
* Most of the ''VideoGame/EarthBound'' [[GameMod ROM Hack]] ''VideoGame/{{Unearthed}}'' takes place underground, with several locations having underground villages with their own species and ecosystems. You do go to the surface on occasion, but it's often for minor things such as getting items.

* In ''Webcomic/SluggyFreelance'', the tunnels beneath Kesandru House (or where it once stood) were originally just a squat stretch of bare earth that Bun-Bun hung out in. But then the Dig-Bots (tiny, self-replicating robots designed to improve the living space) got to work. Eventually they built their own night club down there, and [[http://sluggy.com/comics/archives/daily/20100201 their own mall]].
* Some dragon cities in the comic [[http://www.drunkduck.com/Dragon_City Dragon City]] are in various human cities (such as Dragon City New York). Most sewer workers in those cities know about the dragons.
* The ''Webcomic/GirlGenius'' version of Paris has large sections of its population living underground.

[[folder:Web Original]]
* [[Podcast/WelcomeToNightVale Night Vale's]] Desert Flower Bowling Alley and Arcade Fun Complex is purported to contain a vast underground city beneath the pin-retrieval area of lane five. However, expectations are confounded when it turns out the city beneath Night Vale is actually [[spoiler:a miniature metropolis]]. Unfortunately, its citizens are still quite dangerous, as [[spoiler:Carlos]] finds out to his peril.

[[folder:Western Animation]]
* ''WesternAnimation/{{Futurama}}'' took on this trope, too, with a civilization of mutants living in the sewers of New New York. However, FridgeLogic can make one wonder why they don't use the ruined buildings rather than make their own junkheaps out of things flushed down the toilet. Maybe it's the running water, or maybe the writers felt that the RuleOfFunny justified the contrast. It is also rumored that there's a freakish race of sub-mutants living in the sewers of Old New York (under the sewers of New New York), but that's just a sub-urban legend.
* A group of homeless underground people, with feline-humanoid friends, were featured in ''WesternAnimation/{{Gargoyles}}''. They took over a secret lab built and later abandoned by a MegaCorp.
* ''WesternAnimation/TheSimpsons''
** Parodied in "Hello Gutter, Hello Fadder", in which the sewers beneath Springfield contain Morlocks, C.H.U.D.s and Mole People (led by Hans Moleman).
-->'''Moleman:''' There is no escape from the Fortress of the Moles!
-->[Otto/Homer's bungie-cord retracts, pulling them upward]
-->'''Moleman:''' Well, except ''that''.
** When Homer told the story of his first trip to New York, which culminated in him falling down an open manhole.
-->'''Homer:''' ...and that's when the C.H.U.D.s came at me.
-->'''Marge:''' Of course you'll have a bad impression of New York if you only focus on the pimps and the C.H.U.D.s.
* The Franchise/TeenageMutantNinjaTurtles live in New York's sewer system.

[[folder:Real Life]]
* In case you thought it was all fiction, check [[http://www.boingboing.net/2006/01/27/thousands_live_in_tu.html this]].
* There were so many catacombs, caverns, tunnels and quarries dug out beneath Rome and Paris that the ground ''is'' like swiss cheese. (buildings began falling into the ground) and had to be filled in with artfully stacked rubble made of the ''bones of millions of plague victims''. Rome's catacombs were reputedly inhabited by persecuted Christians. Easy access to limestone bedrock, which could be quarried and burned to produce mortar and fuel, is probably why these cities grew so large in ancient times. The extensive network in Rome is such that it seriously impedes construction of the city's Metro.
* Watch Cities of the Underworld on History channel.
* Many, many people live underground in Paris, Rome, New York, and possibly other major cities. They range from the occasional traveler (mostly the case in Paris) to the homeless (the case in New York)
** In 2003, the French police found a [[http://www.guardian.co.uk/world/2004/sep/08/filmnews.france 400 square meter cinema]] in Paris's underground, fully equiped with electricity, phone, and a small restaurant. The Parisian police even have a dedicated squad patrolling the underground to chase intruders.
* In 1934, G. Warren Shufelt, working off of a Hopi legend of the Serpent Brothers, went in search of the lost underground city of the lizard people, tunneling a shaft down a thousand feet in downtown LA before eventually giving up.
* The town of [[http://en.wikipedia.org/wiki/Coober_Pedy Coober Pedy, Australia]]. The only reason it exists is because opal was discovered there. Diuring the summer, surface temperatures can reach 50 Degrees centigrade, so the 2000-some residents all live in (quite luxurious) underground houses.
* The ancient city of [[http://en.wikipedia.org/wiki/Petra Petra, Jordan]], carved out of rock. It was recently named one of the New 7 Wonders of the World. Most of these 'buildings' are only façades. It is thought that the carved out buildings are either tombs, temples, offices etc. Most of the daily activities were going on in the camp on the plain between the mountains.
* As noted above in the Shadowrun entry, following an [[http://en.wikipedia.org/wiki/Seattle_Fire enormous fire]] in 1889 and having a constant battle with tidal flooding, the city of UsefulNotes/{{Seattle}} rebuilt its entire business district one story higher, on top of the mostly filled-in ruins of the first version, leaving a motley collection of privately-owned tunnels, many of which exist to this day; some of them have been cleaned out and host tours.
* Theme parks such as Disneyland, interlinked museum networks such as the Smithsonian Institute's D.C. facilities, and major hospital or university complexes worldwide tend to have elaborate networks of tunnels, storage facilities, offices and logistics below ground level, where the guests/patients/students never see them.


[[folder:Anime and Manga]]
* The Inner World is a location in the unique anime sci-fi action anime series ''Anime/SpiderRiders'' that exists deep beneth the planet Earth. There live two subterranean civilizations that live in the Inner World. There are the humans, and the [[BeePeople Insectoid People]] called Insectors/Invectids.
* Subterranean civilizations armed with giant {{Robeast}}s are perhaps the second favorite SuperRobot series antagonist after Alien Invaders. One of the first examples is the Dinosaur Empire of the ''Manga/GetterRobo'' series.
** Followed only a few months later by the Mycenae Empire in ''Anime/GreatMazinger''.
* In a variation, ''ElementalLordCybuster'' has a ''world'' in the middle of the Earth, though this ''might'' be a magical dimension.
** Naturally, this is based of the world of La Gias in the ''VideoGame/SuperRobotWars'' series
* ''Anime/TengenToppaGurrenLagann'' has a DIY version, with caves dug out.

[[folder:Comic Books]]
* Common in comics of yesteryear. ComicBook/{{Superman}}, ComicBook/SpiderMan, The ComicBook/FantasticFour, etc. have all had to deal with angry molemen.
* ComicBook/{{Amulet}}: Sort of; it's implied that Alledia is actually a sort of alternate Earth. But they definitely get there by going down a very, ''very'' long staircase.
* The Terry Fermians in the Creator/CarlBarks story "Land Beneath the Ground".
* ''Comicbook/TheTransformers'' introduced violent "Mutants" who live deep below Cybertron's surface and make a point of hunting any Cybertronian that enters their domain.

* ''FanFic/ThePalaververse'': An extensive underworld exists beneath Theia’s surface, permeating the planet’s entire volume down to its core in a maze of tunnels and caverns, underground rivers and plumes of lava rising from seas of magma. The uppermost layers are (relatively) tame and home to the underholds and mines of the Diamond Dogs, but the deeper levels are home to things like sapient colonies of fungi, living patches of darkness or poisonous gas, blind and flightless cave dragons and the Dwellers Below, {{eldritch abomination}}s spawned by primal and chaotic magic. Supposedly, the Diamond Dogs originally lived in the planet’s very heart, but migrated upwards to their current location after an apocalyptic “Creation War” between unspecified empires turned the planet’s core into a sea of molten rock.

[[folder:Film -- Animated]]
* ''WesternAnimation/TheIncredibles'' parodies the tendency for comic book super villains to come from here with the Underminer at the end of the movie.
--> "I am always beneath you, but nothing is beneath me!"

[[folder:Film -- Live-Action]]
* An uncharted cave in ''Film/TheDescent'' hosts a group of Gollum-like, blind, stunted little cave people with remarkable agility and bat-like sonar capabilities.
* The underground civilization in ''[[{{Franchise/Superman}} Superman and the Mole People]]'' reveals itself when a deep well penetrates the rock around it.
* The 1976 Doug [=McClure=] movie ''At The Earths Core'', which is based on the Literature/{{Pellucidar}} stories of Creator/EdgarRiceBurroughs, mentioned in the literature section below.
* In ''Film/ThePhantomMenace'', the planet Naboo is riddled by a tangle of flooded caverns inhabited by gigantic fish and monstrous leviathans, used by the Gungans, who live in its uppermost reaches, as a swift but risky path through the planet. The humans living on the [[{{Arcadia}} paradisiacal surface]] are apparently completely unaware of this, as they happily build their cities and homes along the shorelines of bodies of water that lead directly into the monster-filled abyss.

* In ''Literature/MoreInformationThanYouRequire'', the Mole Men live here with thir hideous steeds and the Trogloditic men. Fortunately for mankind, the Mole Men are relatively nice 18th Century Enlightenment-types
* In the 1930 short story "The Mound" written by Zealia Bishop (but ghost-written by none other than Creator/HPLovecraft) a Spanish conquistador descends into a blue-litten underground world of caverns called K'n-yan. In true Lovecraftian fashion, this world proves only the first of a succession of otherworldly abysses. Below K'n-yan is the grotesque red-litten world of Yoth and below that is the nightmare realm of un-litten N'Kai.
* The ''Literature/{{Pellucidar}}'' novels of Creator/EdgarRiceBurroughs also qualify, with one big "cavern" consisting of the ''entire core of the Earth'', complete with an internal miniature sun! Literature/{{Tarzan}} even went down for a visit in one installment.
* In Creator/DavidEddings' ''Literature/TheBelgariad'', the Ulgos have lived in the caves below Ulgoland for centuries. They are featured particularly in ''Magician's Gambit''.
* Haven City, home of the fairy folk in the ''Literature/ArtemisFowl'' series. Given the quantity of [[AppliedPhlebotinum Phlebotinium]] to which the Fey have access, Haven City is really more an ElaborateUndergroundBase than a simple Beneath The Earth dwelling.
* Underland in Creator/CSLewis's ''The Silver Chair'', the fourth (or sixth, depending whether you go chronologically or by date published) book of ''Literature/TheChroniclesOfNarnia''. However, the topmost layer is all the protagonists get to visit; turns out there is a world much ''much'' further down below called the Land of Bism.
* The ''Literature/{{Tunnels}}'' series. Although ostensibly children's novels, the series is surprisingly dark as well as surprisingly good, and is set almost entirely in a CrapsackWorld which lies beneath our own.
* Creator/JulesVerne's ''Literature/JourneyToTheCenterOfTheEarth'' takes place primarily in a complex network of caves beneath the surface of the Earth, accessible through volcanic vents. There’s even a subterranean ocean, the Lidenbrock Sea, which fills a single titanic cavern, is lit by constant electrical storms, and is inhabited by [[PrehistoricMonster Prehistoric]] {{Sea Monster}}s.
* Creator/TadWilliams' ''Literature/MemorySorrowAndThorn'' series heavily utilizes this trope. Not only is the Hayholt, capital of Erkynland, built atop the ruins of the [[TheFairFolk Sithi]] city of Asu'a, but the entire continent of Osten Ard seems to be riddled with caverns and tunnels, the majority of which were constructed or at least "tamed" by the Dwarrows over countless eons. The Dwarrows use these tunnels to travel from one ancient city to another while remaining completely unobserved by mortals and Sithi alike. The tunnels beneath the Hayholt in particular are a major plot device - TheHero Simon gets lost there no less than three times and they are used by various factions to bypass the castle walls during the [[StormingTheCastle final battle]]. Further, they serve as a metaphor for Simon's CharacterDevelopment.
* ''Literature/TailchasersSong'' has Vastnir, [[spoiler: a nightmarish place populated by various mutant cats and enslaved normal cats, run by fallen god Grizraz Hearteater.]]
* [[OurDwarvesAreAllTheSame Every dwarf ever]]. The most famous modern example (and the one most other portrayals are largely based on) is Creator/JRRTolkien's ''Literature/TheHobbit''.
* ''Literature/TheDescent'' and ''Deeper'' are novels dealing with the revelation that our entire Earth is riddled with this trope, and that cannibalistic near-human creatures inhabit the global maze of tunnels.
* The ''Literature/AgeOfFire'' series has the Lower World, a network of tunnels and cave systems said to be home to most of the surviving dragons. It is often mentioned during the first two books but only rarely and briefly explored. In contrast, most of the third takes place there; it turns out that the Lower World is not only absolutely ''massive'', but may well be just as populous as the Upper.
* [[Creator/HPLovecraft Lovecraft]] ''lives'' on this trope. Pick a story, pick any story, 9 times out of 10 there's some chance that the "long-lost subterranean civilization of awkward syllables" will be mentioned.
* The animals in Creator/RoaldDahl's Literature/FantasticMrFox build a labyrinth of caves and tunnels to live in and steal food from the rather nasty human villians.
* The kingdom of Subterranea in the Franchise/DocSavage novel ''Murder Melody'' (although it takes the heroes about half the novel to actually get there).
* In the ''Franchise/StarTrek: Literature/{{Rihannsu}}'' series, the Romulan/Rihannsu colony world Ysail is famed for its vast Saijja Caverns, a network of caves so vast and deep that they cannot be accurately scanned from orbit and have never been mapped. When the Rihannsu government becomes more oppressive in the later books, most of the Ysailsu retreat to the deepest explored parts of the caves, which become an excellent base for LaResistance.
* ''{{Literature/Dinotopia}}'' has the World Beneath, which was home for many years to the dinosaurs, who hid there to escape cataclysms in the outside world. Later, refugees from the sunken city of Poseidos hid there to try and restart their factories that built their robotic beast-vehicles, but they failed, abandoning the 'strutter-works' and handing over their treasure to the tyrannosaurs for safe passage through the Rainy Basin.
* ''Literature/TheBooksOfEmber'': The City of Ember is a [[spoiler:post-apocalyptic bunker the size of a city]] that was built inside a colossal natural cave. Leaving it or entering it involves a climb up or down steep natural tunnels and a trip down an underground river.

[[folder:Live-Action TV]]
* All the Fraggles of ''Series/FraggleRock'' lived in an elaborate cave hidden behind Doc's workshop. Or beneath the lighthouse, in the UK version. In both cases, exactly where the Gorgs' garden was in relation to the human world was completely unexplored.
* In ''Series/TheYoungOnes'' episode "Boring", our heroes are all bored out of their skulls. Meanwhile, just below their house, the king of the underground kingdom where nothing boring ever happens laments the fact that he may never meet a boring person.
* An inversion occurs in the ''Series/{{Farscape}}'' episode "Taking the Stone". Our heroes land on a "royal cemetery planet" where the surface is covered in the graves of deceased royalty and a society of young hippies live in underground caverns. Moya's crew discovers that the inhabitants are suffering from the effects of radiation which is amplified by the caves. Unlike most examples, the safer thing to do is return to the surface, even with all the graves...
* It's not well explored, but Hollow Earth in ''Series/{{Sanctuary}}'' fits here.
* ''Series/DoctorWho'':
** The Silurian city in the two-parter "[[Recap/DoctorWhoS31E8TheHungryEarth The Hungry Earth]]"[=/=]"[[Recap/DoctorWhoS31E9ColdBlood Cold Blood]]", which lay in a cavern many miles beneath rural Wales.
** In "[[Recap/DoctorWhoS2E5TheWebPlanet The Web Planet]]", Ian meets pale, flightless descendants of the Menoptrans, who'd survived underground for generations since the Zarbi took over the surface of Vortis.
* ''Series/MythQuest'' has Alex venture underneath the Earth and into Hades to rescue Euridice.

* The 1974 concept album ''Music/TheLambLiesDownOnBroadway'' by Music/{{Genesis}} (back when they were a prog-rock band) tells the story of a teenage street punk named Rael who gets sucked into a [[DreamLand surreal world]] beneath the streets of New York City, where he encounters a variety of bizarre inhabitants and situations.
* Music/TomWaits' wonderfully disturbing song "Underground" (A quote from which tops this very page) from ''Music/{{Swordfishtrombones}}'' is all about this.
* The song "Aghartha" by the drone doom band Music/SunnO crosses this trope with EldritchLocation in its lyrics.

* OlderThanPrint: In both the ancient [[Myth/NorseMythology Norse]] and [[Myth/CelticMythology Celtic Mythologies]], certain supernatural folk lived underground or within and beneath hills and mountains.
* We'll call it "mythology" for lack of a better term...during the late 19th Century and early 20th, a number of people became convinced that the Earth was hollow, and inside there was a lush paradise of eight-foot-tall blonde genius-poets who were, in many cases, hermaphrodites, usually supposed to be the perfect ancestors of humans. John Symmes even got some support from Congress to go look around the North Pole for an entry-hole. (John Hodgman covered this in his second book, but he wasn't as far off as you might expect.)

[[folder:Newspaper Comics]]
* ''ComicStrip/FlashGordon'' has the Cavern World of Syk, home of the Blue Magic Kingdom ruled by the Witch Queen Azura. That's beneath ''[[PlanetaryRomance Mongo]]'', not Earth.
* ''ComicStrip/PrinceValiant'' has the subterranean realm of the Dawn People. The current storyline has Val traveling through it to rescue Aleta, encountering monsters and what-not, in something very reminiscent of an old-school [[TabletopGame/DungeonsAndDragons D&D]] dungeon crawl.

* In ''[[VideoGame/ProPinballFantasticJourney Pro Pinball: Fantastic Journey]]'', one of the player's Adventures is to use a DrillTank and travel to the Center of the Earth.

[[folder:Tabletop Games]]
* A subterranean world is a common fixture throughout ''TabletopGame/DungeonsAndDragons''.
** In ''TabletopGame/ForgottenRealms'' and ''TabletopGame/{{Greyhawk}}'', it's called the Underdark, and both use it in more or less the same way -- a very hostile environment filled with ancient evil races where EverythingIsTryingToKillYou.
** In 4th edition, legend has it that it most large tunnels in it were carved out by the blind, agonized strugglings of Torog, God of Imprisonment and Torture, to escape after he was entombed alive during the Dawn War against the Primordials, smashing through the dimensional walls between the mortal world, the Feywild and the Shadowfell in his efforts.
** In ''TabletopGame/{{Eberron}}'', the underworld is called Khyber after the primordial dragon-god from whose body it was purportedly created. Khyber is a world of pitch-blackness, ruled by {{Eldritch Abomination}}s from Xoriat, the realm of madness. Cults of surface-dwellers worship the mutagenic energies that emanate from its black crystals.
** ''TabletopGame/{{Ravenloft}}'' didn't have an underworld that spanned the entire setting, but one of the islands in the Mists was built on taking this trope to its most horrible conclusion -- Bluetspur, home of the mind flayers. Also, the Arak lived in a Beneath the Earth environment before the Shadow Rift appeared, while the domain of Timor relocated to lie underneath that of Paridon.
** The [[TabletopGame/{{Mystara}} Known World]] (later renamed ''Mystara)'' took this the whole nine yards and made the world ''hollow,'' lined with pocket societies placed there by the Immortals to preserve ancient cultures and organisms that had gone extinct on the surface. This setting was called, sensibly enough, the ''HollowWorld.'' The planet's crust between the Hollow World and the surface also had the typical cavernous underworld, inhabited mainly by the shadow elves.
* In ''TabletopGame/{{Pathfinder}}'', the world beneath is known as the Darklands and draws inspiration from pulp fiction of the early 1900s, such as Creator/EdgarRiceBurroughs's ''Pellucidar''. It's divided into three layers:
** The uppermost layer, Nar-Voth, consists of extremely deep and extensive but otherwise fairly normal caverns (which are often isolated and do not form a continuous network), and is the most familiar layer to the surface-dwellers. While most of it is sparsely populated stony wilderness, it is also home to fairly normal humanoids like [[OurGoblinsAreDifferent goblins]], [[LizardFolk troglodytes]] and [[OurDwarvesAreAllTheSame duergar]].
** Sekamina, the middle layer, consists of much larger and more thoroughly interconnected caverns and tunnels, extending beneath most of the world’s surface. It is home to more reclusive and dangerous races like the [[OurElvesAreBetter drow]] and [[OurGhoulsAreDifferent ghouls]], who rule true underground empires, alongside monsters such as [[SpiderPeople driders]], [[TheMorlocks morlocks]] and [[Franchise/CthulhuMythos gugs]]. It has more exotic terrain than Nar-Voth, including fungal forests, volcanic caves and a true subterranean sea.
** Finally, the deepest level -- the Vaults of Orv -- is as much a subject of fear and mystery for the people of Nar-Voth and Sekamina as the Darklands as a whole are for surface-dwellers. It consists of massive caverns the size of nations, some dark and others lit by artificial suns or glowing crystals, containing environments such as deserts, rainforests, ruined cities, mountain ranges and a vast subterranean ocean. The Vaults are inhabited by a great variety of monsters, ranging from dinosaurs, dragons, [[BigCreepyCrawlies monstrous arthropods]] and the undead to a variety of [[EldritchAbomination unspeakable horrors]]. They did not form naturally, but were excavated by a powerful earth elemental {{Precursor|s}} race called the Xiomorn to host their evolutionary experiments.
** The Darklands also extend beneath [[FarEast Tian Xia]] in the far east, although there they are home to creatures such as oni and the [[Franchise/CthulhuMythos Denizens of Leng]] rather than the races of the western Darklands.
* The Subterran Uprising from ''TabletopGame/{{Monsterpocalypse}}''.
* The Skaven in ''TabletopGame/{{Warhammer}}'' have a vast "under-empire" centered under the ruins of Skavenblight, with tunnels stretching all over the world.
* The [[OurDwarvesAreAllTheSame Mountain]] [[OurElvesAreBetter Folk]] in ''TabletopGame/{{Exalted}}'' live Underground in a ForeverWar against the Darkbroods, monstous races inhabiting even deeper tunnels far below the FlatWorld. This was caused by the Solar Exalted, who grew jealous of them, and forced Autochthon (their maker) to geas them into staying underground unless an Exalted said they could come up. Autochthon had the appropriate [[WhatTheHellHero response to this]], and [[ScrewThisImOuttaHere left to Elsewhere]].
* The Underneath in ''TabletopGame/{{MagiNation}}'' is home to a large city and fungus jungles.

[[folder:Theme Parks]]
* The ''Journey to the Center of the Earth'' attraction at [[Ride/DisneyThemeParks Tokyo DisneySea]] is based around this concept.

* ''Toys/{{Bionicle}}'':
** Onu-Koro and Mangaia.
--->'''Lewa''': Has anyone noticed how every time we go underground something bad happens?
** There's also [[spoiler: a "universe" under the island of Mata Nui. It's not ''technically'' underground, being inside of a HumongousMecha that crashed onto the planet a thousand years ago, but from the perspective of the Matoran...]]

[[folder:Video Games]]
* The RTS ''Cave Wars''. True to form, your resource-management includes ensuring a good mushroom-harvest...
* Wherever you don't find sewers in ''VideoGame/CityOfHeroes'', you'll find caverns, with entrances in every park and abandoned lot. The caves tend to house either trolls (former humans mutated by exposure to a drug that induces super powers), beings of living stone, or the various groups of evil magicians. Occasional inter-dimensional aliens may be spotted, usually busy redecorating the place into an ElaborateUndergroundBase. [[LampshadeHanging Lampshaded]] at least once in the intro text to a mission, describing your character wondering how any of the buildings in the city keep standing when the ground below is like Swiss cheese.
* In ''VideoGame/DeadlyRoomsOfDeath'', the great underground empire is actually more advanced than the simple agricultural society above.
* The RPG series ''VideoGame/{{Exile}}'' (and its remake, ''VideoGame/{{Avernum}}'') takes place in a gargantuan network of underground caverns, stretching for several kilometers in every direction, and varying from huge caves big enough to have their own weather systems, to twisting little mazes of passages, all alike. As the name of the area suggests, the people who live there didn't CHOOSE to do so, and sure enough, the place is littered with fungus, lava, and plenty of gloom. Many surface towns also have monster-infested sewers.
* ''VideoGame/FinalFantasyIV'' contains an enormous, open-space underworld, populated by dwarves.
* The Locust from ''VideoGame/GearsOfWar'' live in a vast series of underground caverns known as The Hollow.
* The ''VideoGame/{{Myst}}'' series of PC games gradually reveals that the lost city of D'ni is in a five-mile-wide cavern somewhere beneath a vast stretch of desert in New Mexico [[note]]There's some early ambiguity about it being there or in Egypt, with Cyan Worlds "[[LiteraryAgentHypothesis claiming]]" that since the Myst saga is based on a true story and a real archeological find conscience dictates that they keep the location a secret, but a sign near the property entrance in Uru identifies the specific county, and promotions for the game gave the exact coordinates where the Cleft is supposed to be[[/note]]. One game in the series actually permits a virtual exploration of D'ni itself.
* The ''VideoGame/{{Warcraft}}'' games have their share of underground caverns.
** Azjol-Nerub, the capital of the Nerubian civilization, is a sprawling underground labyrinth that stretches across much of the continent of Northrend. The part where the Nerubians used to live is called the Upper Kingdom, and below that is the Old Kingdom, which consists of even deeper tunnels populated by nameless horrors and one of [[EldritchAbomination the Old Gods]], which was confirmed to be Yogg-Saron in the ''Wrath of the Lich King'' expansion.
** The first 40-man raid instance in ''VideoGame/WorldOfWarcraft'', Molten Core, is a huge lava-filled cavern located deep under Blackrock Mountain. It's home to elementals, lava giants, core hounds and Ragnaros, the elemental lord of fire.
** The Undercity, the vast subterranean home base of the Forsaken, built underneath the ruins of another city.
* The Sierra adventure game ''VideoGame/TorinsPassage'' has no less than four separate worlds Beneath the Earth, each one nested inside the other. In the outermost world, being banished to the Lands Below is a form of capital punishment.
* The original ''VideoGame/{{Zork}}'' text-based game features exploration of the Great Underground Empire.
* ''VideoGame/DwarfFortress'' has implemented no fewer than three levels of world-spanning underground cavern systems, home of mushroom forests, tribes of [[BeastFolk animal people]] and some very weird and hostile monsters, with each layer getting progressively nastier than the last. [[SerialEscalation Dig down past all three of those]], and you'll find a great sea of magma and "semi-molten rock". [[spoiler:And beneath ''that'', if you can contrive to get at it, is {{Hell}}, which can be surprisingly easy to reach, provided you can find the right veins of mineable rock and have a decidedly casual attitude towards being slaughtered by sheep monsters made of ice.]]
* ''VideoGame/MasterOfOrion 2'' has the Subterranean racial trait. Being a tunneling sort means that your colonies can support a greater population, and ten points are added to to trooper effectiveness when defending against a ground invasion.
* The underground in ''VideoGame/{{Touhou}}'' has its own city, and is also stated to be a former hell. Currently inhabited by {{youkai}} that were considered creepy and unpleasant by other youkai. Not really the nicest place around.
* ''VideoGame/AgeOfWonders'' has two map layers (until Shadow Magic added the third), with caves allowing access to the Underground level.
* ''VideoGame/BaldursGateII'' has the Underdark, a vast subterranean labyrinth covering much of the world.
* The Underdark is revisited in the ''VideoGame/NeverwinterNights'' ExpansionPack fittingly titled ''Hordes of the Underdark''. Several fan-made ''NWN'' modules feature the location prominently, as well: an Underdark essentially identical to the one found in Forgotten Realms forms a bulk of Part Two of ''VideoGame/ADanceWithRogues'', despite its setting being otherwise an original ConstructedWorld.
* The ''Franchise/DragonAge'' series features the Deep Roads, a vast subterranian network of artificial caverns and passages dug out by the dwarves in the heyday of their civilization. It had once consisted of hundreds of underground cities named "thaigs" and the miles-long tunnels connecting them, but ever since the [[CataclysmBackstory First Blight]], all but two of them have been overrun by the [[TheLegionsOfHell darkspawn]]. One thaig, Orzammar, is the capital of modern dwarf civilization and is visited in ''VideoGame/DragonAgeOrigins''.
* ''Franchise/TheLegendOfZelda'':
** ''VideoGame/TheLegendOfZeldaOracleGames'' feature the Subrosians, who live in the realm of Subrosia right underneath Holodrum.
** ''VideoGame/TheLegendOfZeldaSkywardSword'''s backstory explains how TheDarkTimes in Hyrule began when a great army of demons emerged from the earth and ravaged the land in their campaign to obtain the Triforce.
** ''VideoGame/TheLegendOfZeldaBreathOfTheWild'' says that Calamity Ganon emerged from beneath Hyrule Castle a century ago to unleash its genocidal rage upon the land. [[spoiler:You end up fighting Ganon in the giant underground Sheikah laboratory where it had presumably been sealed up to that point.]]
* ''Videogame/{{Quake}}'' has a secret level named "The Underearth".
* ''VideoGame/DarkSouls'' has the player spend a lot of time in a variety of underground areas, such as demon infested lava ruins and the Tomb of the Giants.
* ''VideoGame/{{Minecraft}}'':
** In order to get anything done in the game, you need to create labyrinthine tunnels deep underground while mining, which is more or less inevitably going to result in a complex maze of tunnels extending from your base -- and you need to burrow quite deep to get to the best ore.
** Natural caves are procedurally generated like every other landform, and get bigger and more extensive the deeper down you go, together with an increasing likelihood for separate caves having connections with each other. Near-surface caves are fairly small and modest, but the ones near the bottom of the game world can get very big indeed, and are almost always interlinked, resulting in huge underground networks. Naturally, these caves are pitch dark unless you light them up with torches, and as such are crawling with hostile monsters[[note]]most ''Minecraft'' monsters only spawn below a certain light level[[/note]]. Underground lakes and rivers are also common, as are lakes and waterfalls of lava that provide the only natural light down there.
* ''VideoGame/TheElderScrollsVSkyrim'' has Blackreach, a giant cave the size of a small country, housing an ancient [[OurDwarvesAreDifferent Dwemer]] city complex. This, as well as other Dwemer ruins throughout Skyrim, have largely been taken over by the Falmer, a race of subterranean goblin-like creatures who were once the graceful Snow Elves but were taken in and twisted by the Dwemer when their race was threatened by the invading [[HornyVikings Nords]].
* Nearly every single ''Franchise/TombRaider'' game will have Lara Croft explore an underground cavern at some point that are filled with [[EverythingTryingToKillYou traps, water, lava, wild animals, and sometimes a T-Rex]]. While she also explores underground urban areas as well, caves are usually more common in the franchise.
* ''VideoGame/VividConceptions'': Beneath the Earth is where the miniature Bantam civilization dwelled before dinosaurs even existed, and where the game takes place.
* ''VideoGame/{{Turok}} 2: Seeds of Evil'' has the Lair of the Blind Ones, whose centuries spent in darkness has rendered them eyeless as well as giving them [[WeakenedByTheLight a lethal sensitivity to sunlight]].
* The ''VideoGame/{{Heroes of Might and Magic}}'' franchise has cavernous underground levels as a series fixture, sharing many resources and sites you can visit with the surface world, and having unique ones too. There's usually an evil faction that specializes in being there (named Dungeon in several of the games) and other (mostly evil) factions might be more or less at home down there. From map to map, the caverns range from nothing to a vast, sprawling system that has as much open space as the surface world or even more.
* The majority of ''VideoGame/DeadlyRoomsOfDeath'' takes place below the surface. Beethro is exploring King Dugan's 25-level dungeon when he finds passages leading to even deeper dungeons, and eventually to the Rooted Empire.
* Most of ''VideoGame/CryOfFearTheHole'' takes place underground, where Simon wanders dark mine tunnels and strange mazes.
* In ''VideoGame/{{Dominions}}'' the nation of Agartha is based on this. Initially populated by the native Pale Ones, humanoids that can grow to gigantic size, they begin to die out and are replaced by humans who take to worshiping them as the Ages progress.
* Deep below the surface of Britannia in ''VideoGames/{{Ultima}} V'' is the Underworld, a wild neverland of linked caverns and river rapids that collapses at the game's end. In ''Ultima VI'' you can proceed through the ruins and reach the other side of the flat earth.
* ''VideoGame/LostEmber'' has "moles"[[note]](actually fairy armadillos, but ViewersAreMorons, so they're called moles)[[/note]] who live in and around a network of tunnels. When transformed into one, you can also dig your way under obstacles and create your own new tunnels.

* From ''Webcomic/SluggyFreelance'':
** Most of what is seen of the Dimension of Pain seems to consist of caverns; the mostly canonical "Meanwhile in the Dimension of Pain" guest strips confirm that there is a surface above them.
** [[http://sluggy.com/comics/archives/daily/20091228 The Valley That Time Forgot In The Center Of The Earth!!!]]
-->"The valley was actually several hundred miles from the center of the Earth, [[DoesThisRemindYouOfAnything but any mole person suggesting the surface did not revolve around them was fed to dinosaurs]]."
* ''Webcomic/GirlGenius'' has [[http://www.girlgeniusonline.com/comic.php?date=20060508 Deepdown]]. It's [[http://www.girlgeniusonline.com/comic.php?date=20060712 big]].
-->'''Lars''': ...how big can these tunnels ''be''?
-->'''Maxim''' (ex-''cavalry''[[strike:man]][[SuperSoldier jager]]): How big?! Ho ho! [...] it took us ''two years'' to get outta ''dose'' caverns.
* The dragon cities in the comic [[http://www.drunkduck.com/Dragon_City Dragon City]] that aren't in sewers, are in caverns, much like Dragon City Chicago (before the cave-in), where the webcomic primarily takes place. In fact, this is how dragons escaped the mass extinction that wiped out the dinosaurs.
* ''Webcomic/WooHoo'' features a vast Subterrain, a network of caverns, subways and urban areas, formed when a section of the city sank underground during an earthquake.
* 25th Baam from ''Webcomic/TowerOfGod'' was trapped for years inside an underground cavern before the plot started.
* In ''Webcomic/EverydayHeroes'', [[http://eheroes.smackjeeves.com/comics/2162218/home-deep-home/ Hornswoggle and family]] live in an AbsurdlySpaciousSewer.
* This is the main setting of ''Webcomic/{{Drowtales}}'', where the bulk of Drow civilization consists of a handful of large subterranean city-states within large caverns in an extensive underworld, separated by large stretches of stony wilderness home to isolated outposts, driders, degenerate Drow MoleMen, and the few Dwarf nations the Drow didn't wipe out. It was created alongside the [[FloatingContinent sky world]] during the first of two apocalyptic wars waged by ancient elves when a substantial piece was broken from one of the moons and [[ColonyDrop fell to earth]], with the underworld being, in essence, the cracks in the world that impact caused. At least one section, the [[Myth/NorseMythology Nidavellir]], is open to the sky[[note]]in fact, it's the impact crater from said moon fragment falling[[/note]] but filled with a sea of fog. There's also a second underworld under a different continent from the main one, ruled by its own Drow nation, Hel. It's not a nice place.

[[folder:Web Original]]
* ''Wiki/SCPFoundation'': [[http://scp-wiki.wikidot.com/scp-2622 SCP-2622]] claims to be from a subterranean world straight out of pulp fiction, home to a civilization of MoleMen, [[LizardFolk evil reptilian people]], and [[LostWorld caverns full of prehistoric life]]. [[spoiler:He's making everything up.]]
* In ''Blog/CrossingKevinsCrossing'' it is rumored that none of the building have basements because of 'tunnels beneath the ground and weird people that live there'.
* ''WebAnimation/{{Dreamscape}}'': [[GuardianEntity CHEN]] normally resides in the center of the planet.

[[folder:Western Animation]]
* ''WesternAnimation/AvatarTheLastAirbender'':
** The Earth Kingdom's capital of Ba Sing Se was once a subterranean city built within crystal catacombs carved out by Earthbenders. Following expansion, the caverns were abandoned and the lost city is now know as Old Ba Sing Se.
** The Fire Nation capital (built in the caldera of a dormant volcano) also has a series of underground tunnels, which are mainly used as a defense bunker in case of emergencies.
* The leprechauns in the ''WesternAnimation/ChipNDaleRescueRangers'' episodes live in underground places, too, which in the case of the leprechaun king Darby Spree can be pretty spacey.
* ''WesternAnimation/MyLittlePonyAndFriends'' has the Dell Dwellers from "Mish Mash Melee" and the Kingdom of the Lava Demons from "Quest of the Princess Ponies".
* ''WesternAnimation/MightyMax'', gives us Skull Mountain, located deep underground and surrounded by magma, which is [[BigBad Skullmaster]]'s abode, having been banished there thousands of years ago.
* ''WesternAnimation/MyLittlePonyFriendshipIsMagic'' has the Diamond Dogs from "[[Recap/MyLittlePonyFriendshipIsMagicS1E19ADogAndPonyShow A Dog and Pony Show]]", a group of subterranean dog-men who inhabit a labyrinthine system of tunnels and large caves.
* The Mole People featured in ''WesternAnimation/TheTick'' are actually a peaceful but weird group who didn't want to conquer the surface world but to just take a vacation. The Lava men on the other hand...
* ''WesternAnimation/NedsNewt'' has trolls living beneath the Earth's surface, who sometimes try to TakeOverTheWorld, only to be stymied by the protagonists.
* ''WesternAnimation/TheNewAdventuresOfSuperman'': In "The Neolithic Nightmare", Jimmy Olsen falls into an underground pocket populated by malevolent creatures, including dragons, rocs, and giant spiders.
* The Carlocks from ''WesternAnimation/RegularShow'' live in caverns that extend from the park's crash pit and subsist on whatever is thrown into the pit, mostly food left in the busted up old cars.
* ''WesternAnimation/StarWarsTheCloneWars'':
** In "Mercy Mission", R2 and 3PO end up wandering about the cave system beneath the surface of planet Aleen. There they encountered the inhabitants, who included tree-like humanoids and the frog-like fairy Orphne, were causing earthquakes, trying to seal the breach between them and the surface, because surface air was poisonous to them.
** In "Bounty", Asajj Ventress and Boba Fett's crew visited a planet, Quarzite, which was inhabitable only below the surface. At the time the two native species, the Belugans and Kages, were engaged in a CivilWar.
* Trolls from ''WesternAnimation/{{Trollhunters}}'' originate from deep within the Earth, just as humans come from the surface. Because of this [[spoiler:and because most Trolls turn to stone when in contact with daylight]], Trolls usually dwell in vast caverns and other underground spaces.

[[folder:Real Life]]
* Deep caverns permeated by sulfur gases are one of the major refuges for Archaea, ancient prokaryotes that dominated the primordial Earth before oxygen levels rose in the atmosphere. A far cry from dinosaurs, but still a "lost world" ecosystem that persists underground, billions of years after being displaced from much of the planet's surface.
* [[http://en.wikipedia.org/wiki/Karst Karst topography]], formed by water slowly eroding through soluble bedrock over long periods of time, tends to produce impressively extensive cave systems. The largest and most well-known of such caves is probably Mammoth Cave in Kentucky.