[[quoteright:358:http://static.tvtropes.org/pmwiki/pub/images/Hollow_Earth.jpg]]

->'''Old man:''' ''Years ago, I climbed the mountains, even though it was forbidden.''\\
'''Kirk:''' ''Why is it forbidden?''\\
'''Old man:''' ''I am not sure, ''(writhes and gasps in pain from a control device)'' but things are not as they teach us. [[TitleDrop For the world is hollow and I have touched the sky]].''
-->-- ''Series/StarTrekTheOriginalSeries'', "For the World Is Hollow and I Have Touched the Sky"

So, mainstream scientists today believe that the Earth under our feet has a lot of molten rock and metal filling it and have gathered a lot of pretty solid evidence for it. The only complication is that we've never been able to send a human down more than several miles to actually study it up close, largely because NoOneCouldSurviveThat. Which is why since times that are OlderThanRadio, early scientists, writers and more than a few crackpots have believed that there just might be something...or indeed, someone (say, UltraTerrestrials)...down there, possibly powered by a suitably sized sun in the center.

The most known early example is Creator/JulesVerne's ''Literature/JourneyToTheCenterOfTheEarth'', although he likely drew from theories of his time. When science started to switch over to the modern view of Earth's composition the idea of the hollow earth became a DiscreditedTrope, but later generations of SpeculativeFiction writers [[{{Reconstruction}} took up the concept and revitalized it]]. SciFi works bring us hollow world concepts such as the DysonSphere, which is a HollowWorld [[UpToEleven taken to a solar system scale]], and other variations of [[ThatsNoMoon artificially constructed worlds]].

Note that its usual configuration, with people walking about on the inner surface, wouldn't work; a hollow sphere has ''no'' net gravitational pull on any object inside it (although some theorists, such as [[http://en.wikipedia.org/wiki/John_Cleves_Symmes,_Jr John Symmes]], claim that this actually ''could'' work due to the [[http://en.wikipedia.org/wiki/Centrifugal_force centrifugal force]] caused by the planet's rotation. However, it would still have to be very low, otherwise the planet itself would break apart [[note]] The centrifugal acceleration at Earth's equator is only 0.003g[[/note]]).

A related belief is that of "Concave Hollow Earth": that Earth is actually a hollow bubble inside an infinite mass of rock.

A sub-trope of WorldShapes and, in more modern works, an example of AllTheoriesAreTrue. Compare BeneathTheEarth, DysonSphere. When the inhabitants don't know they're in a hollow world, it may become CityInABottle.

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!!Examples

[[foldercontrol]]

[[folder:Anime & Manga]]
* The Fushigiboshi in ''FushigiboshiNoFutagoHime'', which gives it its name (which translates to "Mysterious Planet").
* Dr. Suzuki in ''TransformersCybertron'' believes the world is hollow, with a hole at the North Pole leading to the inside. She's wrong, but there is a big massive cavern full of ancient Decepticons.
* This is a main plot point in ''SpiderRiders''. Hunter finds the Inner-World in the very first episode.
* One ''{{Doraemon}}'' comic centers around Nobita and Doraemon's discovery of a barren, hollow realm in the center of the Earth thanks to a gadget which warps any myth into reality in the eyes of its users. As you would expect from an adventurous kid and his multipurpose robot, the duo proceed to populate the space with life, including little clay people that rapidly form a fairly advanced civilization and eventually venerate the duo like gods.
* This is used in ''LightNovel/MaoyuuMaouYuusha''. The "no gravitational pull" aspect is got around by having the ''sun'' be a ''repulsing'' force instead, pushing things away from it toward the ground.
* The setting for most of ''{{Children Who Chase Lost Voices}}'' is Agartha, a massive underground world with a completely open sky. Any physical or geological impossibilities with this can seemingly be explained by the fact that ''God lives here''.
[[/folder]]

[[folder:Comicbooks]]
* In TheDCU, [[TheWarlord Skartaris]] was originally inside a Hollow Earth. A later {{Retcon}} changed it into an alternate dimension that was accessed through gates at the Earth's poles.
* Another DCU example: Steve Conrad, a [[TheGoldenAgeOfComicBooks Golden Age]] adventurer, explored a LostWorld called Mikishawm inside the Earth.
* ''[[http://en.wikipedia.org/wiki/Valérian_and_Laureline Valerian and Laureline]]'' [a French comic]: The inhabitants of the "starless country" live inside a hollow planet. The core is their sun. And yes, somewhere a physicist is crying.
* There's a ''{{BPRD}}'' story ''called'' "Hollow Earth". It features mutant cavemen and what looks like Nazi submarines. However, it's not quite a traditional version - it's more like there is a network of subterranean caves in various places around the world where said mutant cavemen (really former servitors of the ancient Hyperboreans) live, and most of the world seems to be largely as we know it aside from that. Agartha and similar legends from Theosophy and the Thule Society occasionally crop up in the broader ''ComicBook/{{Hellboy}}'' universe but the truth is generally rather off from what the Theosophists thought.
** The spinoff comic ''Witchfinder'' has a malevolent spirit explicitly exploiting a group's beliefs in the Hollow Earth to feed off their collective life forces (and then their blood).
* In one issue of the Gold Key ''WesternAnimation/{{Underdog}}'' comic book of the 1970s, Underdog met many strange creatures, including a rock 'n' roll band, as he followed Simon Barsinister's drilling machine through the earth.
* In the MarvelUniverse, Saturn's moon Titan is this: barren on the outside, fully inhabited on the inside.
* In the miniseries ''Comicbook/BatmanOdyssey'', Batman travels BeneathTheEarth and finds it hollow and filled with dinosaurs, trolls, wizards, monsters, and so forth. [[http://en.wikipedia.org/wiki/Neal_Adams#Advocacy_of_Expanding_Earth_theory Neal Adams]] is on board with this idea.
[[/folder]]

[[folder:Films]]
* The movie ''TheMolePeople'' featured a team of scientists going [[Recap/MysteryScienceTheater3000S08E03TheMolePeople down, down]] beneath the surface of the Earth to find another society of humans, along with the eponymous Mole People.
[[/folder]]

[[folder:Literature]]
* ''Literature/JourneyToTheCenterOfTheEarth'' implies that there is a second sun at the core of our own planet, meaning we live on the outside of such a sphere. At the time, before the discovery of radioactive elements, this was [[strike:the mainstream]] [[PopularHistory one of several speculated]] [[strike:scientific]] explanations for the Earth's internal heat.
* Creator/EdgarRiceBurroughs cemented the concept in pulp with Pellucidar, an internal world where he set several of his stories, including a notable crossover with Tarzan at Earth's Core.
* ''ChooseYourOwnAdventure: The Underground Kingdom'', which had a star in the middle of the earth and an advanced civilization living inside of the crust.
** Likewise ''Through the Black Hole,'' in which the planets in the black hole appear to be spherical and smooth (and repel all other objects), but can be burrowed into with some difficultly to locate the lush wildlife and SufficientlyAdvancedAliens on the inside.
* Creator/OlafStapledon's ''Literature/StarMaker''.
* Creator/RobertSilverberg's ''Across a Billion Years''.
* Colin Kapp's ''Cageworld'' series.
* Bob Shaw's ''Orbitsville''.
* ''Farthest Star''
* ''Wall Around a Star''-- the inhabitants mainly lived on the ''outside'' of the Sphere (or in the various layers of the Dyson Shell).
* The eponymous structures in George Zebrowski's ''Macrolife''.
* The John Gribbin novel ''Innervisions''. This is meant to be a shock ending to the book, except [[TrailersAlwaysSpoil the cover announces]] "The world was a sphere ... and they were inside it!"
* In the sci-fi novel ''Literature/PrisonersOfPower'' by [[Creator/StrugatskyBrothers A. and B. Strugatsky]], the inhabitants of the planet Saraksh are convinced that they live on the inner surface of a spherical cavity, due to the unusual optical properties of its atmosphere (the horizon looks like it is '''above''' the observer).
* Due to a combination of its gravitic and atmospheric oddities, the world of [[http://en.wikipedia.org/wiki/Mesklin Mesklin]] in Creator/HalClement's hard sci fi classic ''Mission of Gravity'' was thought by its inhabitants to be bowl-shaped. They were incorrect (it was actually a very flattened spheroid).
* {{Hell}} in Creator/PhilipJoseFarmer's ''Inside Outside''. According to some characters, it used to be flat but changed as scientific knowledge advanced. [[spoiler:It's later revealed, however, that this is false and that hell is a space station.]]
* In the semi-sequel to ''Literature/TheTimeMachine'', called ''The Time Ships'' (by Creator/StephenBaxter), the time traveller returns to the future once again, but finds it changed. The Morlocks are now "good" in this future, and are also incredibly advanced, having engineered a [[DysonSphere hollow sphere]] around the Sun slightly inside Earth's orbit. Morlocks live on the outside of this hollow sphere in the dark, while the Eloi live on the sunlit inside of it.
* Also by Creator/StephenBaxter, a short story called "[[http://kasmana.people.cofc.edu/MATHFICT/mfview.php?callnumber=mf907 Shell]]" is set on a planet that has been ''folded in on itself'' in the fourth dimension. There is no sky -- people looking up see the other side of the planet curving over them, as if it's a shell. When one character uses a hot-air balloon to explore the other side, she witnesses the "shell" flatten out and then become curved normally, [[AlienGeometries while the land she just left curves into a shell over the sky]].
* In the Literature/ArtemisFowl series, the Fairies moved to inside the HollowEarth in recent times - that or BeneathTheEarth depending on how you interpret it.
* Nehwon in Fritz Leiber's Literature/FafhrdAndTheGrayMouser stories is a concave hollow world.
* The interior of Onyx in ''{{Halo}}: Ghosts of Onyx'' (part of Halo's ExpandedUniverse) has a portal to one of these.
* In one of Creator/IsaacAsimov's stories in the rather epic Robots/Empire/Foundation chronology, some of the inhabitants of Trantor believe the universe to be an infinite mass of earth and rock, punctuated by occasional life-bearing bubbles. It is worth noting that the truth is more along the lines of BeneathTheEarth, but only the (increasingly rare and alienated) scientific and technical elite still believe this, with the others believing such a belief to be a quite frankly bizarre conspiracy, the details of which I can't quite remember.
* In Robert Rankin's ''The Greatest Show Off Earth'', our world is [[spoiler:the inner layer of]] a hollow world (in a kind of matryoshka style). [[spoiler:The inhabitants of the outer layer are planning to plug up the holes at the poles because they are fed up with our pollution spilling out.]]
* Margaret Weis and Tracy Hickman's Literature/TheDeathGateCycle's second book, Elven Star, features one of these, where all the stars in the sky are [[spoiler: the equivalent of gigantic lighthouse beacons]].
** The world of elemental Water is another example, with the slight difference that the islands are floating in air-bubbles in a vast sea - meaning that people travel around in submarines instead of airships - and the world of elemental Fire is another variation on this theme.
** Even the world of elemental Air apparently is this according to the map, even though the "walls" presumably consist of some kind of force fields rather than solid matter. The final book implies that all the worlds exist in what used to be our solar system, and can be reached through mechanical rockets even after the Death Gate is closed - after you get through the planets' artificial crust, in any case.
* ''Literature/MoreInformationThanYouRequire'' features a long section on the mole-manic societies dwelling within the hollow Earth, including a list of 700 mole-man names and countless allusions to many of the other works listed on this page.
* In the ''{{Tunnels}}'' series, the Earth's core is hollow and contains an Eden-like paradise called "The Garden of the Second Sun".
* The Franchise/IndianaJones novel ''Indiana Jones and the Hollow Earth'' is [[CaptainObvious about]] [[ExactlyWhatItSaysOnTheTin this]]. More specifically, Indy discovers Ultima Thule (see "Real Life" examples below).
* ''Hollow Earth: The long and curious history of imagining strange lands, fantastical creatures, advanced civilizations, and marvelous machines below the Earth's surface'' by David Standish goes into detail on the fictions, theories, and wacky religions inspired by this trope, but even he doesn't bother listing all the stories based on this trope (it was, for example, quite popular in the 19th century to base utopian fiction inside a hollow earth).
* In Creator/JohnCWright's ''[[Literature/TheGoldenOecumene The Golden Transcedence]]'', the agent of the Silent Oecumene claims that they live inside a black hole, which has been hollowed out and so exerts no gravitational pull on them.
* ''Literature/TheWhiteDarkness.'' A girl is dragged along by her eccentric uncle to find the entrance to the hollow earth in Antarctica. [[spoiler: He's wrong, and quite insane.]]
* The Shellworld(s) in Iain M. Banks's ''Literature/{{Matter}}'' is essentially a nesting-doll series of these, although all the inhabitants live on the "outside" of each shell. What's on the inside? Why, artificial stars, some of which roll across the sky and some of which are fixed.
* ThomasPynchon's ''Against the Day'' seems to have this. [[MindScrew It's unclear]].
* ''[[Literature/GreatShip The Great Ship]]'' is a [[CoolStarShip hollow starship]], about the [[PlanetSpaceship same size as Jupiter]]. It has a hollow core large enough to contain an entire world, [[DeathWorld Marrow]]. The rest of the ship is full of thousands of fuel tanks that can fit moons, and even more caverns designed for habitation.
* Creator/UmbertoEco's novel ''Literature/FoucaultsPendulum'' pokes fun at this trope, together with many others commonly believed by conspiracy theorists.
* The [=BookWorld=] in the ''Literature/ThursdayNext'' series eventually reboots and turns into one of these in ''One Of Our Thursdays Is Missing''. Used to be the various books were floating in space independent of each other, but they now occupy a single continent.
* A variant in Creator/NikolayNosov's children's book ''Dunno on the Moon'', where the Moon turns out to not only be hollow but actually housing a mini-Earth inside it. The only difference for the shorties (all people in the book series are shorties, small humans) living on the mini-Earth is that, at night, everything is dark. Some technobabble explains how they get any light at all during daytime (something about cosmic rays turning into visible light when passing through the Moon's crust). The Moon-shorties have no idea that they are living inside a planetoid, as they don't have rockets yet and, frankly, have no need to try to figure out how to get into space (being a thinly-veiled stand-in for Western capitalists, most Moon-shorties are greedy and corrupt and, as such, are uninterested in the advancement of their people; this is the first book where the concept of money is brought up, when an Earth-shortie goes to a restaurant and tries to leave without paying). Another big difference (that is actually a big plot-point) is that, while on regular Earth all fruits and vegetables are huge compared to the shorties (as it "bigger than the shorties" in some cases), all fruits and vegetable on the mini-Earth are in proportion to them. Thus, for those living on the mini-Earth, hunger is a real possibility. After explaining who he is to two Moon-shorties, Dunno tells them that their rocket on the Moon's surface is full of seeds of giant fruits and vegetables. The three of them try to market that idea and create a fund for building a rocket to get from mini-Earth to the Moon's surface and retrieve the seeds. Unfortunately, without "moonite" (an {{Expy}} of Creator/HGWells's cavorite) that can only be found on the Moon's surface, building a rocket is extremely difficult, as shown by the second expedition sent from Earth (the rocket is much smaller and most of it is devoted to fuel; the first rocket, equipped with "moonite" only needed a little bit of thrust and was luxurious by comparison).
[[/folder]]

[[folder:Live-Action TV]]
* They also turned up in ''Series/StarTrekTheNextGeneration'' and ''Series/StarTrekVoyager''.
** [[Series/StarTrekTheOriginalSeries TOS]] episode "For The World Is Hollow And I Have Touched The Sky" had a variation, a shell covering an artificial planetoid to hold the atmosphere in.
* The ''Series/BabylonFive'' station could technically be considered a "world" of this sort.
* ''{{Lexx}}'''s [[spoiler:planet Fire]] has an inner surface with inexplicable bright daylight and Earth-normal gravity. Given its supernatural nature, one can only shrug.
* In ''{{Sanctuary}}'' it turns out that the Earth really is hollow. And the only people that knew were [[spoiler: Jekyll and Hyde]].
** It's actually populated by technologically-advanced humans and Abnormals who have migrated underground in order to escape the vampires ruling the world at the time.
* The [[DoctorWho Fourth Doctor]] story "The Pirate Planet" gave this an interesting twist. Zanak was a gigantic hollow planet with enormous [[TeleportersAndTransporters transmat engines]] at its core. It could literally materialize around smaller planets and squeeze them of their wealth and energies.
* The ClockPunk opening sequence to ''GameOfThrones'' takes place on at the very least a parabolic version of the world map of Westeros and Essos with an astrolabe floating above it functioning as both the sun and the TitleCard for the show.
[[/folder]]

[[folder:Tabletop Games]]
* The indie HollowEarthExpedition is all about this, using the fluidity of the pulp genre to meld the hollow earth with Thule, Atlantis, and prehistoric times, and any sort of lost civilization, and the whole thing is discovered on the cusp of WorldWarII. Hey, how else are you going to feed Nazis to dinosaurs?
* The Hollow World is a ''TabletopGame/DungeonsAndDragons'' game setting inside another D&D game setting, being located inside the planet {{Mystara}}.
** ''TabletopGame/{{Spelljammer}}'' got Herdspace described in ''The Maelstrom's Eye'' by Roger E. Moore -- a crystal sphere with an internal surface (the size of a "small" solar system) covered with inhabitable landscape, much like a naturally occurring DysonSphere.
** ''TabletopGame/{{Pathfinder}}'', as a nod to ''Pellucidar'', has a inverted vault in it's Underdark-analogue, complete with otherwise-extinct animals. it's more like a mini-world than an actual hollow planet, though; an ancient terrarium of Sufficiently Advanced...somethings.
** The ''World Builder's Guidebook'', a supplement for 2nd Edition D&D, discussed variant WorldShapes, including hollow worlds. Notably, it points out that the same blank globe-maps it provides for Earth-like spherical worlds are also perfectly usable for a hollow sphere.
* ''TabletopGame/GeniusTheTransgression'' has the Hollow Earth as one of its many bardos - pocket realities created when established science is proven wrong. From the presence of things like "brontosaurs" and Piltdown Men, it's implied to be a catch-all for [[SomewhereAPaleontologistIsCrying every paleontological blunder ever committed]].
** It's also been recently taken over by [[StupidJetpackHitler Nazis]]- to be precise, [[TheHeartless Manes]] formed at the end of WW2 when the real Nazis were crushed and almost all faith in their ideology crumbled.
* There is some mentions in the TabletopGame/{{Warhammer 40000}} rulebook about hollow worlds.
* The plane of Mirrodin (formerly [[spoiler:Argentum]]) in ''MagicTheGathering'' is hollow, and mostly metallic. There are five channels, called lacuna, through which one of the planes five suns emerged from the mana core. There are five lacunae, one for each color of mana, and one for each of Mirrodin's five suns.
* The [[TabletopGame/WorldOfSynnibarr Synnibarr]] roleplaying game's titular planet is hollow. According to the backstory, Earth's sun was becoming unstable, and because Earth itself was physically unsuitable, the planet's stellar engineers took Mars and expanded it, hollowed it out, and terraformed it until it was completely unrecognizable to serve as a new home for the evacuated human race. Overlaps with ThatsNoMoon, as a suitably huge power generator was installed in Synnibarr's core to power the artificial planetary heating and atmosphere systems as well as the engine designed to propel the planet to a new star system to take up orbit in. After dozens of catastrophes, wars, and invasions during the 40,000 year journey, the inner core of the planet was abandoned, with the planetary machinery almost completely inaccessible at the top of a thousand-mile high mountain ascending to the planet's geographical core.
[[/folder]]

[[folder:Videogames]]
* ''VideoGame/{{Terranigma}}'' has this at the beginning, and later the protagonist drops through a hole to find himself on the surface of Earth.
* The world of La Gias from ''VideoGame/SuperRobotWars'' (only visited in the GaidenGame ''LordOfElemental'', but referenced throughout the series) is like this. Its specifically in the center of the Earth, but its more of a magical dimension.
* ''VideoGame/ShinMegamiTenseiIIINocturne'': At TheEndOfTheWorldAsWeKnowIt (roughly 30 minutes into the game), the city of [[TokyoIsTheCenterOfTheUniverse Tokyo]] becomes the new world, with the central "sun" waxing and waning every few days.
* Atrea, the world in ''VideoGame/{{Aion}}'' was hollow with the Tower of Eternity through the center as the [[PhysicalGod manifestation of the god Aion]] who provided the inside of the world with heat and light. However, after the [[EarthShatteringKaboom Cataclysm]], the center of the tower and a good deal of the planet's equator were destroyed leaving an apple-core shaped world held together only by magic. Although the planet orbits a nearby star, only one half of the planet gets any light from the star.
* Macbeth from the original ''VideoGame/StarFox'' is stated to be a hollow planet, but in truth there ''is'' a core, albeit smaller than the crust that surrounds it. This makes a huge series of caverns that covers the entire planet. Andross had plans to turn Macbeth into a massive base, in other words, a naturally formed ''Death Star'' (without the superlaser).The actual stage even takes place with the Arwings flying around inside the planet.
* ''VideoGame/TheSecretWorld'' features a transit network between the various locations across the world, built into the depths of the hollow earth; known as Agartha, said transportation is based around the roots of the WorldTree itself, and is attended to by a number of hulking [[{{Golem}} Golems]] and one eccentric Victorian stationmaster.
* The world of ''VideoGame/DwarfFortress'' may or may not be spherical, but it's hollow alright, as your dwarves may discover [[DugTooDeep the hard way]]. Specifically, [[spoiler:it has a sort of "swiss cheese" layering of an unminable rock called slade which is covered in semi-molten rock and adamantine, depending on where.]]
* ''VideoGame/FinalFantasyIV''. It has a unique configuration in that, instead of two habitable surfaces opossed to each other, the Underworld IS the basic, solid planetary sphere, while the Overworld encases it. As proof, the Tower of Bab-Il rises from the Underworld and continues ''upwards'' through the Overworld. The Underworld is also considerably smaller, and, being located between the solid sphere and its shell, it lacks a Sun. The magma flowing through it is more than bright enough to do the job, though.
* Most of ''VideoGame/FinalFantasyXIII'' takes place on Cocoon, a Hollow World roughtly the size of North America were it rolled up into a ball. Humanity resides on the inside surface area off the sphere, which is comprised of several distinct landmasses and oceans, and a giant freaking hole to nowhere. Cocoon floats in the lower atmosphere of Gran Pulse, a planet somewhat larger than Earth, given the apparent scale of Cocoon in comparison to it. Nothing about Cocoon makes sense scientifically, but it works anyway thanks to [[AWizardDidIt a million-some]] {{Physical God}}s [[AWizardDidIt forcibly willing it to do things like float above Gran Pulse, and have a fuctional atomsphere, gravity, and a day/night cycle]].
* The final area of ''VideoGame/DragonQuestIV''. Also used in ''VideoGame/DragonQuestIII''.
* ''VideoGame/SepterraCore'' takes place on seven massive continents or "Shells" whose orbit and level are controlled by a [[MasterComputer central core]] with [[MagicalComputer mythical wish granting powers]].
* Some of the planets in both ''VideoGame/SuperMarioGalaxy'' and ''VideoGame/SuperMarioGalaxy2'' resemble hollowed out spheres covered with huge holes and a [[UnrealisticBlackHole black hole]] underneath. If you fall into the black hole, you die. Also, the boss battle against [[EverythingsEvenWorseWithSharks Kingfin]] takes place inside a hollow planet, and in the case of the final battle against [[BigBad Bowser]], a hollow ''Sun''.
** The Spin-Dig Galaxy level from ''VideoGame/SuperMarioGalaxy2'' appears to be located inside one of these.
* ''Xardion'' has the Hollowsphere (Zikar), which is icy on the outside and jungle on the inside.
[[/folder]]

[[folder:Webcomics]]
* ''Webcomic/SchlockMercenary'' has the Buuthandi, built by the F'sherl-Ganni. Due to math they're rather more like spherical solar sails counterbalanced with living habitats (drastically reducing the living space compared to a standard Dyson Sphere-- only a few hundred thousand times Earth rather than millions), but allow them to tame an entire star as a source of energy and mass.
* In ''Webcomic/{{Homestuck}}'' [[spoiler:The Battlefield has a very thick crust with a hollow center housing THE TUMOR (Before being removed) in its center.]]
* ''Webcomic/ReptilisRex'' is based on the premise that Hollow Earth is real and that the LizardFolk living in the center are forced to leave and integrate into human society [[FantasticRacism with limited success]].
* Webcomic/AxeCop features a civilization of people living within the Moon rather than on top. The Moon Ninjas come from here.
[[/folder]]

[[folder:Web Originals]]
* The Web site [[http://www.psypets.net/ PsyPets]] has this as part of its FramingDevice; you're a volunteer working for the Hollow Earth Research Group (HERG). However, "Hollow Earth" in this setting is not ''actually'' inside Earth; rather, it's just a ''name'' given to an alternate dimension because the researchers were reminded of the old myth. References to the actual "Hollow Earth" pop up sometimes, though.
* In ''AHDotComTheSeries'', a Hollow Earth appears that combines [[ShoutOut Shout Outs]] and [[{{Homage}} homages]] to just about every Hollow Earth in fiction. It first appears in "Dinos and Nazis and Deroes, Oh My!" and, [[spoiler:in a TearJerker, is destroyed in "Harbingers"]].
* [[http://www.facstaff.bucknell.edu/dgriffin/Research/Griffin-HE_in_Science.pdf What Curiosity in the Structure: The Hollow Earth in Science]] by Duane Griffin, is a short historical paper surveying scientific thinking about the hollow earth up to the present day.
* [[http://www.thehollowearthinsider.com/news/index.php The Hollow Earth Insider]]
* In ''TheSalvationWar'', Heaven and Hell are both Hollow Worlds. This is partly due to the linguistic convention of saying that one is "on" earth but "in" hell or heaven. They have AlienGeometries in other ways as well; traveling in what appears to be a straight line on them results in a curved path.
[[/folder]]

[[folder:Western Animation]]
* The city of Arkadia and the other "strata" in ''SpartakusAndTheSunBeneathTheSea''.
[[/folder]]

[[folder:Real Life]]
* As alluded to above, this was an early theory of the Earth's structure dating back to the 1800. And like the [[FlatWorld flat earth]] theory, some people on the fringes continued to advocate it.
** The [[http://en.wikipedia.org/wiki/Theosophical_Society Theosophical Society]] were believers - their philosophy held all religion to have some virtue, all races were equal and they would promote studies in science, philosophy and religion. Popular through the early 1900s.
** The [[http://en.wikipedia.org/wiki/Thule_Society Thule Society]] were less charitable - their beliefs influenced the Nazi doctrine of Aryan supremacy and Nazi mysticism.
* As recently as 2007, some guy got some attention for his fundraising for an expedition to the poles to enter the holes to the hollow earth supposedly located there.
* An unfalsifiable (and therefore scientifically irrelevant) claim is that the earth is in fact a hollow sphere with the universe inside and geometry transformed to match (i.e. the closer in you go, the smaller you get).
* David Icke believe this is where the Nazi leadership escaped to. He also believes that the holes are enormous and that's why commercial planes never fly near the poles. (Planes frequently fly over the poles as a way to cut down on travel times. It's easier to fly to Russia from Canada by flying over the poles than to go west.)
* Edmond Halley (of Halley's Comet fame) was one of the earliest proponents of the Hollow Earth as a scientific theory rather than a legend or religious belief. He speculated that Earth was made of a several hollow spheres (akin to Russian Nesting Dolls) that rotated independently of each other. He came up with this theory as a way of accounting for variations in the behavior of magnetic compasses; his idea was that something below the surface (the aforementioned spheres) was causing interference.
[[/folder]]

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