[[caption-width-right:264:[[VideoGame/HotelMario "Gee... it's kinda dark."]] [[labelnote:Games]]Clockwise from top left: ''VideoGame/SuperMarioBros1'' (''All-Stars'' release), ''VideoGame/DonkeyKongCountry1'', ''VideoGame/TheLostVikings'', ''VideoGame/SuperMetroid'', ''VideoGame/KirbySuperStar'', ''VideoGame/{{Plok}}''.[[/labelnote]]]]

Underground levels, carved out of endless expanses of rock, are among the favorites of video game designers, primarily because they can shape these tunnels and cavities to any sizes, shapes and lengths they desire without having to resort to the InsurmountableWaistHighFence.

Sometimes known as the Underworld, this setting appears frequently as a direct contrast to TheOverworld as it is where the hero goes when he enters a cave or falls in a hole. It could be an EmptyRoomPsych, a [[DungeonCrawling full fledged dungeon]], or anything inbetween.

Visitors may encounter BottomlessPits, falling rocks, stalactites, breakable walls, [[FungusHumongous giant mushrooms]], [[LethalLavaLand lava]], an [[UnderTheSea underground lake]], and/or [[MinecartMadness minecarts]]. GoddamnedBats abound, and watch out for the [[UndergroundMonkey monkeys]]. Visitors will probably ''not'' encounter stalag''mites'', because game designers prefer flat, uninterrupted floors for the characters and enemies to walk along (though stalagmites may show up from time to time as the cavernous version of SpikesOfDoom). The music often gets more low-key and adds drums and bass.

In most cases, light is strangely never a problem -- it might be darker than usual, but you've [[HollywoodDarkness always got enough to see by]] (maybe there's some sort of [[BioluminescenceIsCool glowing fungus]]). Oddly enough, although spiders are common, {{Cobweb Jungle}}s are not.

An extremely common variant is the crystal cave, featuring quartz and precious gems gleaming wall-to-wall with AllNaturalGemPolish. No one ever considers mining them out, because they're just there to look [[RuleOfCool cool]]. And wouldn't you know it, sometimes the crystals are [[SlippySlideyIceWorld ice crystals]].

The RPG version is usually either a fairly difficult dungeon with little reprieve, or the [[NoobCave very first one]], used as an introduction.

May at times overlap with the AbsurdlySpaciousSewer or BlackoutBasement. If there are people living there, see UndergroundCity and BeneathTheEarth. May also encompass the literal [[TheUnderworld Underworld]], though that usually gives it elements of LethalLavaLand or BigBoosHaunt.


%%Please sort this by genre


* ''Franchise/TheLegendOfZelda'':
** ''VideoGame/TheLegendOfZeldaALinkToThePast'' has Turtle Rock, which notably doesn't have any man-made (or even divine) design like the other dungeons, so it's more like a very extended cave.
** ''VideoGame/TheLegendOfZeldaOcarinaOfTime'' has Dodongo's Cavern, the Fire and Shadow Temples and Beneath the Well. The former two are set inside the volcanic Death Mountain, so they also qualify as LethalLavaLand dungeons. The latter two are placed in the underground of Kakariko Village, and them being overrun by undead creatures makes them BigBoosHaunt locations as well.
** ''VideoGame/TheLegendOfZeldaTheWindWaker'' has the aptly named Earth Temple. Since the number of light sources is finite, Link and Medli have to reflect the available light to the dark areas where it's required.
* ''VideoGame/ProjectEden'' is almost entirely set underground. This being a scifi game, underground means "abandoned and decaying ruins of the megacity that now spans above" rather than "damp caves". Occasionally overlaps with BeneathTheEarth, as a few game areas are inhabited by neutral [=NPCs=].
* In ''VideoGame/StarFoxAdventures'', once the speeder bike in the Darkice Mines passes a certain point, the rest of the level is cave.

[[folder:First Person Shooter]]
* The entirety of the first two ''VideoGame/{{Descent}}'' games, sometimes crossing into LethalLavaLand. [[JustifiedTrope Justified]] in that you're flying through mines to clear out berserk mining robots.
* ''[[VideoGame/FirstEncounterAssaultRecon F.E.A.R]]'': The expansion ''Perseus Mandate'' has the Old Underground Metro Area, a forgotten city district engulfed by an earthquake and used as a base for the new city. There aren't any human enemies in the two levels it spans, [[ThingsThatGoBumpInTheNight which doesn't make them any less terrifying]]. In fact, the sheer amount of hostile apparitions probably makes the place the games' very first BigBoosHaunt.

* The ancient [[AbsentAliens Vanu]] caverns in ''VideoGame/PlanetSide''. Megalithic rock formations, giant crystals composed of [[NanoTechnology nanites]], multiple vertical levels, zip-lines, and abandoned ([[RagnarokProofing but totally functional]]) Vanu buildings.
* ''VideoGame/WorldOfWarcraft'' has several although Ahn'Kahet qualifies the best. It is an underground city that here and there borders natural subterranean life. It features large, glowy mushrooms, insects of different types and sizes and bioluminiscent birds/bats that fly around. It also contains large number of undead that took over the city as well as the few surviving Nerubians that orginally inhabited the city. While the dungeon itself is fairly linear, players are able get a good view of the massive underground caverns from ledges and combinations of creepy music, darkness and mysterious whispers (courtesy of an [[EldritchAbomination Old God]] under whose range of influence the city is located) make this place quite {{Nightmare Fuel}}lerific. It was originally meant to be part of a whole underground region.

[[folder:Platform Games]]
* Glitter Gulch Mine from ''[[VideoGame/BanjoKazooie Banjo-Tooie]]''.
* Several of the {{Recurring Location}}s in the Franchise/{{Castlevania}} series, such as the aptly named Underground Caverns, Abandoned Mines, and Catacombs, are this. This makes it all the more confusing in [[spoiler:the latter half of]] ''[[VideoGame/CastlevaniaSymphonyOfTheNight Castlevania: Symphony of the Night]]'' [[spoiler:where all three of these levels are the highest points in the game, yet retain the attributes of an Underground Level.]]
* ''VideoGame/CaveStory''. The only thing that's not underground is the surface right before the [[FinalBoss final]] [[BossRush boss]]. However, while that's the official setting, only a few levels look like actual caves; there's a desert level, a grassy outdoorsy level, some techie levels, an a plantation level, among others (most of which have a rocky background). Conversely, The Outer Wall appears to be outside the caves, although it's always night there, whereas it's daytime up on the balcony.
* ''VideoGame/CrystalCaves'' takes place entirely underground, but this is one case where someone is there to mine it out.
* ''Franchise/DonkeyKong'':
** Chimp Caverns from ''VideoGame/DonkeyKongCountry1'', with various other areas also qualifying. Occasionally subverts the "there's always" light, with levels that require you to free a parrot to carry a lantern for you, giving you an annoying flashlight-style lit area. Other stages are lit by torch light and thus have normal lighting.
** ''VideoGame/DonkeyKongCountry2DiddysKongQuest'' improves on this with its mine shaft stages (Namely Kannon's Klaim). It also features giant ice caverns found for the first time in the penultimate world, featuring appropriately echoing and cool-sounding music.
** ''VideoGame/DonkeyKongCountry3DixieKongsDoubleTrouble'' brings back the darker cave levels taking the stage.
** ''VideoGame/DonkeyKong64'' has the Crystal Caves, which combines this with SlippySlideyIceWorld.
** The fourth world of ''VideoGame/DonkeyKongCountryReturns'' is set completely in caverns (and its name is indeed Cave), though they're always navigated through with minecarts or a wooden rocket (including the boss level, as the battle consists of a pursuit to intercept Mole Miner Max).
** Two levels in the Autumn Heights in ''VideoGame/DonkeyKongCountryTropicalFreeze'' mix this trope with LevelAte, as they're calcified caverns that have ''cheese'' in many parts.
* The ''VideoGame/EccoTheDolphin'' games manage to cross this level with UnderTheSea several times. At one point the severely reduced visibility is actually acknowledged, and the use of Ecco's sonar is required to get through.
* ''VideoGame/TheFloorIsJelly'' has a large underground cavern that serves as the HubLevel. The cavern, besides being [[RubberyWorld ridiculously bouncy like everything else]] in the game, is also populated with strange and magnificent flora as well as the occasional frog, the latter causing small wobbles through the ground as they hop around.
* Virtually every ''Franchise/{{Kirby}}'' game has one. ''The Great Cave Offensive'' in ''VideoGame/KirbySuperStar'' and its UpdatedRerelease is a {{Metroidvania}} subgame that takes place entirely in an underground cavern, which is apparently large enough to have its own atmosphere and clouds floating around in places.
* ''Franchise/{{Metroid}}'':
** Most of the first ''[[VideoGame/{{Metroid 1}} Metroid]]'' game is divided between Brinstar (caves) and Norfair ([[LethalLavaLand lava caves]]). It's also the purest example in the series, in that aside from the opening screen and the ending screen, nothing takes place above ground.
** Later games mix things up with Maridia ([[DownTheDrain flooded caves]]), Phendrana Drifts ([[SlippySlideyIceWorld frozen caves]]), and the Phazon Mines ([[GreenRocks irradiated caves]]).
* ''Franchise/SonicTheHedgehog'':
** Mystic Cave Zone from the [[UsefulNotes/SegaGenesis Genesis]] version of ''VideoGame/SonicTheHedgehog2'', and Underground Zone and Gimmick Mountain from the [[UsefulNotes/SegaMasterSystem Master System]] and UsefulNotes/GameGear versions.
** [[LethalLavaLand Lava Reef Zone]] from ''[[VideoGame/Sonic3AndKnuckles Sonic and Knuckles]]'', and the 2P level Endless Mine in ''Sonic 3''.
** Mystic Cave and Quake Cave from ''VideoGame/SonicDrift 2''.
** In ''VideoGame/SonicAdventure'', most of Ice Cap before the snowboarding portion, and the second part of Sonic's version of Red Mountain (the whole level, for Gamma).
** Aquatic Mine from ''VideoGame/SonicAdventure2''.
** The second half of Flame Core in ''VideoGame/SonicTheHedgehog2006'', similar in style to Red Mountain and Lava Reef.
** Skeleton Dome from ''[[VideoGame/SonicStorybookSeries Sonic and the Secret Rings]]''.
** Coral Cave in ''[[VideoGame/SonicRushSeries Sonic Rush Adventure]]'', [[HailfirePeaks mixing it up with]] UnderTheSea. And it's very pretty.
** Crystal Cave from ''[[VideoGame/SonicStorybookSeries Sonic and the Black Knight]]''.
** In ''VideoGame/SonicLostWorld'', both Windy Hill and Silent Forest Zone 3 take place in a dark cave. The latter also contains a few SlippySlideyIceWorld elements to it.
* The various ''Franchise/SuperMarioBros'' levels and bonuses reached by warp pipes:
** World 1-2 of ''VideoGame/SuperMarioBros1'' is the most iconic example, serving as an introduction to a type of setting that contrasts directly with the open-air levels that are more frequent. All five ''VideoGame/NewSuperMarioBros'' games, as well as ''[[VideoGame/SuperMarioBrosTheLostLevels The Lost Levels]]'', do the same thing at exactly the same level slot. In contrast, ''VideoGame/SuperMarioBros2'' and ''VideoGame/SuperMarioBros3'' both introduce the Underground setting in later levels.
** ''VideoGame/SuperMarioWorld'' goes as far as having two worlds themed around caves: Vanilla Dome and Valley of Bowser. The most frequent feature seen in them is a kind of yellow rock that rises and lowers periodically, which becomes benefitial to reach high places in big areas but detrimental when Mario or Luigi is in narrow passageways.
** The 3D Mario games have Hazy Maze Cave from ''VideoGame/SuperMario64'', "Spin-Dig Galaxy" and "Slimy Springs Galaxy" from ''VideoGame/SuperMarioGalaxy2'', and various individual cave levels in ''VideoGame/SuperMario3DLand'' and ''[[VideoGame/SuperMario3DWorld 3D World]]'' (the latter two introducing the setting in World 1-2, in the style of the 2D games).
** Mole Mines in ''VideoGame/SuperMarioRPG: Legend of the Seven Stars'', complete with {{Minecart|Madness}}-riding minigame.
** The area beneath Rogueport in ''VideoGame/PaperMarioTheThousandYearDoor'' is fairly extensive, but it also overlaps with HubLevel and AbsurdlySpaciousSewer, as it's the ruins of the original Rogueport.
** ''VideoGame/SuperPaperMario'' has the Floro Caverns.
** ''VideoGame/PaperMarioStickerStar'' has plenty of underground passages access via warp pipes.
* World 2 of ''VideoGame/MarioAdventure'' is a combination of this and LethalLavaLand.
* ''VideoGame/SuperMarioFusionRevival'':
** World 3-1: Viscous Burrow. The first area our heroes encounter in the Ocean of Oblivion is a burrow inhabited by giant maggots. This area is flooded by caustic purple fluid and at times, the only way to traverse the caustic pools is to use the slime trails produced by the maggots.
** World 4-5 (Crimson Cavern): A maze level that switches between a blood-filled and a lava-filled version of the same cavern, with some minor differences.
* The first ''VideoGame/{{Shantae}}'' game has the Golem Mine, which has lava, stalactites, and stalagmites blocking Shantae's path and puzzles involving the usage of polarities to attract and repel objects.
* The ''WesternAnimation/TazMania'' LicensedGame for the UsefulNotes/SegaGenesis has a cave as the fifth world, with the first act having a MineCartMadness level. The sequel, ''VideoGame/TazInEscapeFromMars'' has Mole World, with [[AdvancingWallOfDoom a giant drilling machine chasing Taz throughout the second act]], which Taz gets to fight in the third.
* In ''VideoGame/TinyToonAdventuresBustersHiddenTreasure'', the ice cave serves as this. Enemies include blue monsters that shoot bubbles, bats, and clones of Perfecto Prep student, [[YouDirtyRat Roderick Rat]]. In addition to them, Buster also has to [[IndyEscape outrun boulders]] and [[StalactiteSpite avoid falling stalactites]].
* ''VideoGame/WarioLand'':
** ''VideoGame/WarioLandSuperMarioLand3'' has many of these in [[DeathMountain Mount Teapot]] and [[LethalLavaLand Stove Canyon]].
** The entirety of ''VideoGame/VirtualBoyWarioLand'' takes place underground.
** ''VideoGame/WarioLandII'' has the chapter "Go to the Cellar!!", which also features a LocomotiveLevel.
* The Moon Grotto and Gumo's Hideout in ''VideoGame/OriAndTheBlindForest''.
* ''VideoGame/YoshisIsland'':
** The original game for SNES, ''VideoGame/SuperMarioWorld2YoshisIsland'', plus the sequel for UsefulNotes/NintendoDS'', both have numerous cave levels, which have underground waterfalls (or lava in the case of the respective final worlds' cave level).
** "The Bone Dragon Cave" in ''VideoGame/YoshisStory'' is underground and is the only truly underground level on the second page, even though it is known as The Cave.
* ''VideoGame/{{Athena}}'' has World of Cavern as the second level.

[[folder:Puzzle Games]]
* ''VideoGame/TheWitness'': [[spoiler:The caves underneath the island that are accessed through a passage at the bottom of the mountain.]]

[[folder:Role-Playing Games]]
* ''VideoGame/{{Avernum}}'': The first two games take place entirely underground, and there are underground parts in all the others.
* A great many locations in ''VideoGame/BreathOfFire'' qualify, especially the majority of the early-game dungeons.
* ''VideoGame/ChronoTrigger'' features places like Heckran's Cave, the Reptite Lair, and [[spoiler: the ruins of the Tyranno Lair]] as underground locales.
* ''VideoGame/DarkSouls'' has the Catacombs and the [[BlackoutBasement Tomb of the Giants]].
* ''VideoGame/DungeonSiege'' has many, MANY underground caverns that need to be traversed. These range from standard limestone tunnels to ice crevasses to breathtaking crystal caverns to desert badlands to dragon nests to molten lava tunnels.
* ''VideoGame/FinalFantasy'':
** ''VideoGame/FinalFantasyVI'' has the optional dungeon of The Ancient Castle, which can only be accessed through the tunneling castle, Figaro.
** ''VideoGame/FinalFantasyVII'' has the Mithril Mines, with glowing green rocks.
** ''VideoGame/FinalFantasyIX'' has the Ice Cavern, Fossil Roo, and Gargan Roo.
** ''VideoGame/FinalFantasyXI'' has quite a few areas like this: Gustav Tunnel, Kuftal Tunnel, Korroloka Tunnel, Sea Serpent Grotto, Ordelle's Caves, and Aydeewa Subterrane. And yes, there does seem to be glowing fungi in that last one.
** ''VideoGame/FinalFantasyXII'' has a bunch of these, including the Lhusu mines, Barheim Passage, the Henne Mines, the Sochen Cave Palace, and Zertinan Caverns. One may or may not also include Giruvegan, as the paths and platforms are man-made.
** ''VideoGame/FinalFantasyXIII'' had the Mah'habara Subterra, a network of tunnels dug for whatever reason by the fal'Cie Atomos under the Gran Pulse.
** ''VideoGame/FinalFantasyXIV'' features several, notably in the form of Sastasha, the Tam-Tara Deepcroft, Copperbell Mines, the Thousand Maws of Toto-Rak, Cutter's Cry, Dzemael Darkhold, and Aurum Vale.
* The Underworld in ''VideoGame/KingdomHeartsII'' is [[HailfirePeaks half this and half]] BigBoosHaunt.
* Too many in the ''Franchise/{{Pokemon}}'' games to name them all:
** Each mainline game seems to feature at least 3, [[HailfirePeaks at least one]] is an [[SlippySlideyIceWorld ice cave]], and another one is pitch black and requires the Flash power to navigate with any accuracy. Victory Road is always among them, however. Wherever you are, expect to find plenty of [[GoddamnBats Zubats, Geodudes]], their evolved forms, or whatever batlike or rocklike Pokemon are native to the region.
** ''[[VideoGame/PokemonDiamondAndPearl Diamond, Pearl, and Platinum]]'' have a set of underground passages filled with treasure that spans the '''entire region'''. There are no wild Pokemon, but it's the best place to get items in... any of the games, really.
** Relic Passage in ''VideoGame/PokemonBlack2AndWhite2'' is also notable. It connects Driftveil City to Castelia's sewers, Desert Resort (it's the only way into the Relic Castle then) and Twist Mountain. It lets you ride mining carts in some tunnels and also contains the chamber with the three Golems from [[VideoGame/PokemonRubyAndSapphire Gen III]], though you need the key from the opposite game for the final Golem. The biggest annoyance aside from how easy it is to get lost is that some areas have higher-level Boldore that have access to Explode.
** Terminus Cave in ''VideoGame/PokemonXAndY'', home of [[OlympusMons Zygarde]].
** As for the console games, ''VideoGame/PokemonColosseum'' has the Under, a former mine where many of Pyrite Town's residents fled to after the town's normal state of semi-lawlessness escalated to chaos due to Team Cipher coming to town. It's closed off in ''VideoGame/PokemonXD'' to keep any other criminal activity from going on in it.
** This is the entirety of the ''VideoGame/PokemonMysteryDungeon'' games, and all the other ''[[{{Roguelike}} FushigiNoDungeon]]'' games, for that matter. You do have some areas that take place aboveground, but all the main action happens in underground caverns, hence the 'dungeon' title.
** ''VideoGame/PokemonSnap'' has the Cave stage, but the Factory stage is underground as well as an EternalEngine.
* ''VideoGame/DragonAgeOrigins'' has the Deep Roads, which contain equal amounts of caverns and ruined dwarf strongholds. Also ThatOneLevel for many players, though the abundance of great loot (two of the best sets of armor in the game, and several top-quality weapons, can be found down there) can help make up for it.
* The first ''VideoGame/UltimaUnderworld'' game in its entirety.
* This is a common type of dungeon in ''Franchise/TheElderScrolls'' franchise. ''[[VideoGame/TheElderScrollsVSkyrim Skyrim]]'' alone has regular caves and mines (often serving as dens for bandits, [[TheMorlocks Falmer]], vampires, etc.), ancient Nordic burial tombs, and subterranean fortresses guarded by [[RagnarokProofing machines that were built by their long-since-vanished]] [[OurDwarvesAreAllTheSame Dwemer]] masters. There's even a [[BeneathTheEarth wide-open cavern deep underground]] connecting three Dwemer fortresses, once the location of the Dwemer city of Blackreach.
* The first and second chapters of the Hordes of the Underdark expansion for ''VideoGame/NeverwinterNights'' are (except for the very start) spent underground.
* ''VideoGame/AVeryLongRopeToTheTopOfTheSky'': The Saecelium Mine and the starting cave.
* The ''VideoGame/{{Fallout}}'' series has featured underground areas from the beginning, ranging from the buried Vaults and their entrance tunnels to mines and abandoned subways.
* ''VideoGame/ArcanumOfSteamworksAndMagickObscura'' has a number of mines and underground cities to explore, usually infested with [[BreakableWeapons weapon-eating]] golems and corrisive blobs.

[[folder:Shoot 'Em Ups]]
* The UsefulNotes/TurboGrafx16 game ''Dead Moon'' has a Moon cave stage, though the underground environment here has little significance except parallax-scrolling stalactites.
* ''VideoGame/StarFox1'' has one of these in the planet Macbeth, which is explained away as a planet where the core shrunk due to strange experiments by [[MadScientist Andross]].
* All of ''VideoGame/{{Touhou}} Project: Subterranean Animism'' is like this, as the plot requires the characters to investigate a disturbance coming from the underground. [[spoiler:Except the extra stage, which revisits a location from the previous game. [[note]]The Moriya Shrine. Which also happens to be the location of the previous game's extra stage.[[/note]]]]

[[folder:Wide-Open Sandbox]]
* ''VideoGame/DwarfFortress'': Extensive cavern systems are procedurally generated during world creation. They’re dotted with groves of [[FungusHumongous giant mushrooms]] that can be cut for lumber and home to tribes of primitive [[BeastMan animal people]] that will more likely than not attack your dwarves with poisoned spears and blowguns, and a variety of wildlife ranging from regular cave critters to some [[OurMonstersAreWeird very weird monsters]] to truly terrifying creatures like [[GiantSpider giant cave spiders]] and cave dragons, and the occasional [[EldritchAbomination Forgotten Beast]]. They’re split into three levels, with increasingly dangerous wildlife the deeper you go, and below the third level there’s a world-spanning magma sea, home to various fire elementals.
* ''VideoGame/{{Minecraft}}'': Procedurally generated caverns span the entire game world, getting larger and more interconnected the deeper one goes. Small, solitary surface caverns are easily converted into homes, while the deeper cavern systems provide easy access to lava and rare ores. Cave exploration is not without danger--the mazelike passages and enormous size of the deep caverns make them very easy to get lost in, sudden drop-offs to hard stone or lava pools are common and difficult to spot, and the total darkness complicates both problems, while also meaning that monsters are ''everywhere''. Oh, and they’re the only place where bats are found.
* ''VideoGame/{{Terraria}}'': Everything between the GreenHillZone at the top of the map and the LethalLavaLand the bottom is this, except for the Underground Jungle and the Dungeon.

* As with the aforementioned source material, ''Videogame/TheFellowshipOfTheRing'' has the Mines of Moria, which are [[DisappointingLastLevel extremely long]].
* ''VideoGame/YoungMerlin'' has a cave system with mine carts. There are passages everywhere between various cave entrances--you just step in the entrance and get transported to a different cave entrance somewhere else. Unless you step into the cave entrance and get killed by a bunch of creatures with evil eyes (the only thing you ever see).
* The Hollow from ''VideoGame/PrimalRage''.
* The final levels of ''VideoGame/{{Plok}}'' (pictured above, middle-left) take place in the Flea Pit.
* The entire setting of ''VideoGame/ManicMiner'' ([[CaptainObvious duh]]).
* The "Melon Mines" level of the ''VideoGame/CommanderKeen'' episode ''Keen Dreams'' and the cave levels of ''Secret of the Oracle''.
* Sector 5 of ''VideoGame/{{Jumper}} Two'' is an underground cave which Ogmo fell into ''while asleep''.
* ''{{VideoGame/Turok}} 2: Seeds of Evil'': The Lair of the Blind Ones.
* ''VideoGame/RockRaiders''. ''The entire game'' is an UndergroundLevel.
* Huge chunks of the ''VideoGame/GearsOfWar'' franchise.
* Stage 5 (Maclonna Mine) in ''VideoGame/MoonCrystal''.
* ''VideoGame/PsychoFox'' has two: Stage 5 (Underground Passageway) and Stage 7 (Underground Cavern).
* In ''VideoGame/SlySpy'', the sixth level is in a cavern leading to an underground hideout.
* ''VideoGame/{{Terranigma}}'' has a cavernous dungeon inside the Ra Tree.
* ''[[Videogame/MechWarrior MechWarrior Living Legends]]'' features Thunder Rift, an massive underground cavern full of waterfalls, natural land bridges, with rocks raining down from the hole in the cavern ceiling. It's large enough to justify FutureCopter factories and repair facilities.