History Main / LostWorld

* Downplayed in ''WesternAnimation/GravityFalls'' where the eponymous town has a mine abandoned because miners claimed to see dinosaurs. Turns out lots of prehistoric plant and animal life have been survived in said mine, the dinosaurs at least being preserved in amber.

* New Zealand. Up until about 600 years ago, it was the last major landmass on Earth still dominated by dinosaurs (albeit of the feathered variety): its largest herbivore was the 10-foot-tall flightless moa, while its top predator was the giant Haast's eagle. New Zealand is also home to real-life relics from the Mesozoic such as the Tuatara and the Pepeketua frogs. [[TheMagicGoesAway Then the Polynesians showed up.]]

* New Zealand. Up until about 600 years ago, it was the last major landmass on Earth still dominated by dinosaurs (albeit of the feathered variety): its largest herbivore was the 10-foot-tall flightless moa, while its top predator was the giant Haast's eagle. New Zealand is also home to real-life relics from the Mesozoic such as the Tuatara and the Pepeketua frogs. [[TheMagicGoesAway Then the Polynesians showed up,]] (ancestors of the modern Maori) who hunted the Haast's eagles and Mao to extinction.

* ''Franchise/{{Godzilla}}'': Lagos Island is a fictional island off the coast of Japan. It's subverted in that it can be accessed via plane or boat, but people generally don't live there due to the population of large carnivorous dinosaurs. [[FromBadToWorse Oh, and the island was hit by nuclear radiation]] [[Franchise/{{Godzilla}} mutating said dinosaurs into city-destroying monstrosities.]]

* Film/KingKong's home, which is generally referred to as Skull Island. In the [[Film/KingKong1933 original film]], the island was never named, although its most recognizable feature, Skull Mountain, was named; likewise in the [[Film/KingKong1976 70s remake]], the only reference is to "the beach of the skull".

* '50s BMovie and ''Series/MysteryScienceTheater3000'' feature ''Film/LostContinent'', starring [[Series/Batman1966 Cesar Romero]]. [[LeaveTheCameraRunning And it sure took some finding.]]

* The lost cave complex in the 1956 film ''Film/TheMolePeople,'' in which the titular creatures live. They are enslaved by eil Sumerians who arrived in the caves when escaping a flood thousands of years ago.

** While [[Literature/JohnCarterOfMars Barsoom]] could be considered more of a PlanetaryRomance setting, it is itself full of Lost Worlds, cut off from the larger Barsoomian culture. The clearest of these is the Valley Dor, featured in ''Literature/TheGodsOfMars''.

* The ''[[DeathWorld Zendikar]]'' setting in ''TabletopGame/MagicTheGathering'' is an entire ''plane'' of this, complete with mystical artifacts, hidden ruins of ancient cities and temples and [[DoomyDoomsOfDoom horrible death at every turn]] for everyone from [[{{Mooks}} Goblins]] to ''[[PhysicalGod planeswalkers]]''. [[spoiler: [[JustifiedTrope Justified]] in that it doubles as the [[EldritchAbomination Eldrazi's]] [[SealedEvilInACan can]].]]
* The ''TabletopGame/DungeonsAndDragons'':
** ''TabletopGame/{{Mystara}}'' has a long history with this trope, featured in such classic adventures as "Isle of Dread" or "Night's Dark Terror". The Hollow World boxed set converted the interior of the planet into a massive Lost World a la Pellucidar, chock full of prehistoric creatures and lost civilizations.
** ''TabletopGame/{{Planescape}}'': The Lost Plateau is a great pillar of stone rising in the remote depths on the Beastlands, and those who found their way to it report hearing noises and seeing shapes upon unlike anything else in the plane. The plateau's top is a wide, shallow bowl covered by thick jungle and sloping down to a lake in its center, and is home to thriving populations of dinosaurs -- creatures otherwise entirely absent in the plane -- and a reclusive tribe of green-furred beastmen. There's a great deal of rumor and speculation about it, including the theory that the plateau was raised by ancient powers or the plane itself to create a last haven for the vanishing creatures living there.

* The musical ''Theatre/{{Brigadoon}}'' has its eponymous town surrounded by a mysterious fog in the Scottish highlands. The two American hunters who stumble upon it ask why there is no Brigadoon on the map, and eventually get a good answer: the town and its inhabitants vanished in an 18th century miracle, and only reappear for one day every hundred years.

Besides [[DesertedIsland islands]], [[JungleOpera jungles]], and the [[MysteriousAntarctica frozen poles of the Earth]], The Lost World can exist in even more mysterious places, such as outer space, the [[EldritchOceanAbyss bottom of the ocean]], or [[BeneathTheEarth deep within the planet]] itself. Occasionally treated more seriously, as a venue for playing with alternate evolutionary pathways.

This can happen in RealLife, when the Lost World had been isolated for millennia due to some geological feature which makes travel in and out too bothersome to attempt: the 3 miles wide crater of [[http://en.wikipedia.org/wiki/Mount_Bosavi Mount Bosavi]] is a textbook case, as it had been thoroughly explored just in 2009, [[TruthInTelevision which ended with discovery of at least 40 previously undescribed species]].

* The ''TabletopGame/DungeonsAndDragons'' game-setting of ''TabletopGame/{{Mystara}}'' has a long history with this trope, featured in such classic adventures as "Isle of Dread" or "Night's Dark Terror". The Hollow World boxed set converted the interior of the planet into a massive Lost World a la Pellucidar, chock full of prehistoric creatures and lost civilizations.
* ''TabletopGame/{{Pathfinder}}''

* ''The Land Unknown'' (1957) has a US Navy helicopter in MysteriousAntarctica crashing into a misty crater populated by [[SpecialEffectsFailure highly unconvincing dinosaurs]].

* The lost cave complex in the 1956 film ''The Mole People,'' in which the titular creatures live. They are enslaved by eil Sumerians who arrived in the caves when escaping a flood thousands of years ago.

They are usually found in remote locations, such as the center of large and barely explored continents (usually DarkestAfrica), the polar ice caps, or mysterious islands. They are often home to [[AdvancedAncientAcropolis lost civilizations]] with amazing LostTechnology, or to [[LivingDinosaurs prehistoric animals that have managed to survive unchanged]] -- aside from the fact that they [[PrehistoricMonster suddenly find humans delicious]]. Some Lost Worlds are [[EverythingTryingToKillYou almost ludicrously dangerous]] and populated by fearsome monsters, and still others are {{Magical Land}}s where AllMythsAreTrue. Prone to being destroyed by [[ApocalypseHow volcanic eruptions, floods, quakes, and/or bombs]] [[CataclysmClimax at the end of the book/film/series]], with the protagonists barely escaping.

Besides [[DesertedIsland islands]], [[JungleOpera jungles]], and the [[MysteriousAntarctica frozen poles of the Earth]], The Lost World can exist in even more mysterious places, such as outer space or [[BeneathTheEarth within the planet itself]]. Occasionally treated more seriously, as a venue for playing with alternate evolutionary pathways.

* Fittingly enough, [[http://www.lost-world.com/Lost_World02/inGENe.html this website]] promoting Jurassic Park II is still chugging along, showcasing web design straight out of the age of AOL, complete with animated GIF intro page and image tile background.

[[TropeNamer Named after]] ''Literature/{{The Lost World|1912}}'' by Sir Arthur Conan Doyle, this is, naturally, a geographic location off all maps.

[[TechnologyMarchesOn No longer popular (or even credible) with the arrival of satellite mapping and GPS]]. Most modern fictions that use this trope are set in the pre-satellite past or there's some sort of explanation as to why it hasn't been seen (either AWizardDidIt or there's a kind of EMP over the island). The Lost World has now been adapted to serve in even more mysterious places, such as outer space or BeneathTheEarth. You are now much more likely to see a civilization thought long dead on an episode of Star Trek than on your modern action show.

AppliedPhlebotinum is sometimes used to explain why the area has stayed lost into the modern era; it's contained in a PocketDimension, or was created by aliens as a nature preserve, or some such HandWave. Occasionally treated more seriously, as a venue for playing with alternate evolutionary pathways.

It's worth knowing that some elements of this have happened in RealLife, even recently. However, they certainly don't match the scale of a true Lost World. For example, you might have a tribe that has had no interaction with the outside world for hundreds of years, but not, say, an entire civilization. When it does happen, the Lost World had been isolated for millennia due to some geological feature which made travel in and out too bothersome to try: the 3 miles wide crater of [[http://en.wikipedia.org/wiki/Mount_Bosavi Mount Bosavi]] is almost a textbook case, as it had been thoroughly explored just in 2009, [[TruthInTelevision which ended with discovery of at least 40 previously undescribed species]].

Two frequent lost worlds are the DesertedIsland and (in older works) MysteriousAntarctica. Often a key element in a JungleOpera. May contain a CityOfGold. Overlaps with HollowWorld, with the internal and external surfaces loosing knowledge of eachother. CityInABottle can happen as well, if the Lost World is cut off from the outside world.

* ''WesternAnimation/{{Up}}'': Paradise Falls is a partial invocation of this trope. It's not particularly hidden, as Carl and Russell are able to find it with little more than a lot of balloons and a pocket GPS navigator. On the other hand, the film implies that it has remained unsettled because [[spoiler:the AxCrazy Charles Muntz has been killing off any other explorers who've visited the area]].

* The Kingdom of Prester John, a mythical Eastern Christian monarch searched by [[UsefulNotes/TheCrusades Crusaders]] was said to be located somewhere in Africa or Asia and was home of not only endless riches, but also strange animals (possibly local fauna from the areas whom European Crusaders were unfamiliar with).

* Lost [[InsistentTerminology Places]] discovered in modern days:

** [[http://en.wikipedia.org/wiki/North_Sentinel_Island North Sentinel Island]]. Though known of since the 18th century by other inhabitants of the Andaman Islands and by other since the 19th century, very little is actually known about the island and its inhabitants, the Sentinelese people, who to this day remain one of the most isolated uncontacted peoples in the world. The Sentinelese are extremely hostile to outsiders, such that the Indian government (which has ''de jure'' control of the island, though in practice they are autonomous) arrests anyone who goes anywhere near the island for their own safety. Anthropologists have never been able to travel to the island to study the Sentinelese and their culture, and probably won't anytime soon.
* New Zealand. Up until about 600 years ago, it was the last major landmass on Earth still dominated by dinosaurs (albeit of the feathered variety): its largest herbivore was the 10-foot-tall flightless moa, while its top predator was the giant Haast's eagle. New Zealand is also home to real-life relics from the Mesozoic such as the Tuatara and the Pepeketua frogs. [[TheMagicGoesAway And then the Polynesians showed up.]]

* ''TabletopGame/{{Exalted}}'': The world is full of unexplored or once-civilized places, but the Exalts can take it to the extreme: when [[EldritchAbomination She Who Lives in Her Name]] [[EarthShatteringKaboom destroyed ~90% of the world]], bits and pieces of it were thrown back into the Wyld; theoretically an Exalt with strong Wyld resistance can journey in it find things that were lost, up to and including ''worlds''.

* ''Disney/AtlantisTheLostEmpire'' has the titular Atlantis, whose core sank beneath the earth millennia ago in a last-ditch effort to save Atlantean civilization from a cataclysm they unlashed and which has lingered on to the modern day in a hidden, fertile cavern deep BeneathTheEarth.

* In the ''Anime/SpiderRiders'' franchise, a place aptly named the "Inner World" exists deep beneath the earth in a gigantic cavern filled with plants, an ocean and giant humanoid insects.

* ''VideoGame/VirtualBoyWarioLand'' takes place in a vast subterranean labyrinth located underneath a tropical rainforest.
* ''VideoGame/FinalFantasyIX'' has three unexplored continents on Gaia, with only the Mist Continent being densely populated and civilised. As airships can't run without mist, and there's none on the other continents, travel to them has been rare. The Outer Continent mainly had its population wiped out in a disaster some ten years previously. The Forgotten and Lost Continents meanwhile have no settlements and are home to a few {{Eldritch Location}}s.
* ''[[VideoGame/SoulSeries Soul Calibur III]]'' has the Lost Cathedral crosses over this trope with EldritchLocation. Its a beautifully pristine palace drawing from all forms of European architecture which can only be reached by "those with a strong will and a willingness to bet their own lives", with all characters in the arcade mode managing to reach it in the final stage of the game, where also [[TheAtoner Siegfried]] and [[BlackKnight Nightmare]] have their confrontation.

* The ChristmasSpecial ''WesternAnimation/RudolphsShinyNewYear'' features a few variations of this trope in the Archipelago of Last Years. Where the old AnthropomorphicPersonification of the year goes to retire, they choose an island to live in and TimeStandsStill for everyone in that island. The island where One Million B.C. lives is {{Prehistoria}} of course, and a YeOldenDays year lives on a MagicalLand.

* The episode "Franchise/{{Tarzan}} and the Knights of Nimmr" of the 1970s Saturday morning cartoon ''Tarzan, Lord of the Jungle'' is loosely based on the book ''Tarzan, Lord of the Jungle'' (the setting was largely retained, but the characters and story were replaced with original characters). The two cities were merged into the single city of Nimmr, which had just been discovered by a balloonist at the beginning of the story.
* ''{{WesternAnimation/Superfriends}}'' (1973-74) episode "The Mysterious Moles". Deep under the earth is the Bottomless Cave: a gigantic cavern filled with plants, lakes and dinosaurs.
* ''WesternAnimation/DinoBoy'', aka ''Dino Boy in the Lost Valley'', which aired along with ''WesternAnimation/SpaceGhost''. The title valley had cavemen, dinosaurs and other prehistoric creatures, and several lost civilizations.
* Kong Island in ''WesternAnimation/KongTheAnimatedSeries'' had dinosaurs, mammoths, an evil god with a harpy for a minion and the big ape himself. One of the episodes dealt with the origin of the island due to a time vortex caused by said evil god.

* ''WesternAnimation/BatmanTheBraveAndTheBold'': Dinosaur Island features in "Terror on Dinosaur Island!", "Revenge of the Reach!" and "Four Star Spectacular!".
* One episode of ''WesternAnimation/TheLegendOfTarzan'' had Tarzan and his friends entering Pellucidar, the Lost World from Edgar Rice Burroughs's novels.

* ''Lands of Mystery'', a supplement for the 1980s pulp game ''JusticeInc.'', was all about gaming in a Lost World setting. About half the book was taken up with Zorandar, a setting/campaign that had everything from dinosaurs to a lost Roman colony.
* The ''TabletopGame/DungeonsAndDragons'' game-setting of ''TabletopGame/{{Mystara}}'' has a long history with this trope, featured in such classic adventures as "Isle of Dread" or "Night's Dark Terror". The Hollow World boxed set converted the interior of the planet into a massive Lost World a la Pellucidar, chock full of prehistoric creatures and lost civilizations.
* The ''[[DeathWorld Zendikar]]'' setting in ''TabletopGame/MagicTheGathering'' is an entire ''plane'' of this, complete with mystical artifacts, hidden ruins of ancient cities and temples and [[DoomyDoomsOfDoom horrible death at every turn]] for everyone from [[{{Mooks}} Goblins]] to ''[[PhysicalGod planeswalkers]]''. [[spoiler: [[JustifiedTrope Justified]] in that it doubles as the [[EldritchAbomination Eldrazi's]] [[SealedEvilInACan can]].]]
* ''TabletopGame/SpiritOfTheCentury'' readily embraces this possibility due to its strong 1920s era pulp foundation. While no such places are directly described in too much detail, it's suggested that several exist in DarkestAfrica (most notably, the kinds of places where Gorilla Khan's will is law) and there's a small hint of a lead for a GameMaster to potentially follow about a journey to the Earth's core being planned in the sample adventure provided in the book.

** The titular Hollow Earth is all about this trope, featuring never-ending jungle, lost civilizations, dinosaurs, and increased healing rates.

* ''TabletopGame/{{Exalted}}'': The world is full of unexplored or once-civilized places, but the Exalts can take it to the extreme: when [[EldritchAbomination She Who Lives in Her Name]] [[EarthShatteringKaboom destroyed ~90% of the world]], bits and pieces of it were thrown back into the Wyld; theoretically an Exalt with strong Wyld resistance can journey in it find things that were lost, up to and including ''worlds''.

* ''VideoGame/{{Ultima}}'' loves this trope almost as much as Creator/DCComics:
** In ''VideoGame/UltimaIII'' and ''[[VideoGame/UltimaVII VII]]'', the legendary island of Ambrosia. Particularly odd because in the latter case it would seem to be in the way of shipping.
** In ''VideoGame/UltimaV'', a cavernous Underworld complete with shipwrecked sailor and lost expedition. In ''[[VideoGame/UltimaVI VI]]'' we learn that there's an entire civilization even ''deeper'' underground. [[spoiler:Well, "underground" from OUR perspective. They live on the opposite side of a flat Earth.]]
** ''VideoGame/WorldsOfUltimaTheSavageEmpire'' is set in Eoden, a copy of Doyle's Lost World complete with lost tribes, dinosaurs, and a "Dr. Livingstone, I presume" moment.
** In ''VideoGame/UltimaVIIPartII: Serpent Isle'', Serpent Isle has been missing from the maps since the end of the first game.
* Gaia's Navel in ''VideoGame/ChronoCross'' is at the center of an inaccessable island (you have to be flown there). It's basically 65,000,000 B.C. from ''VideoGame/ChronoTrigger'' in the modern day -- it even has a younger {{Expy}} of Ayla, Leah, who joins your party [[spoiler: and is implied to be her mother]].

* Although dinosaurs are not exactly unknown in the rest of the world, Un'Goro Crater of ''VideoGame/WorldOfWarcraft'' has a distinct Lost World design.
** The Sholazar Basin in Northrend also qualifies.
** And as of ''Mists of Pandaria,'' the Isle of Giants.
* The ''VideoGame/{{Turok}}'' {{FPS}} videogame series, which were loosely based on the comic book, although the player character is a modern day Native American who gains access to modern weapons during the course of the game.
** See above, the player character rampages through the 'Lost World' valley (among other settings) that the original comics were set in.
* The DS port of ''VideoGame/ChronoTrigger'' adds the [[ThatOneSidequest Lost Sanctum]], which allows a village of reptites to survive at least until the middle ages. Inside of a mountain, so it's somewhat understandable that no one can find it.

* ''VideoGame/EVEOnline'' recently jumped on this trope with wormholes that open up into "Sleeper" space. Along with several other races they were thought to be extinct. WildMassGuessing ranges from time loops to returns to Earth's galaxy though they are much more advanced now. WordOfGod has been very silent on the matter. Also Earth itself qualifies due to the collapse of the Eve Gate.
* ''VideoGame/SkiesOfArcadia'' has Ixa'taka, a lost continent beyond the supposedly impassable South Ocean.
* In ''VideoGame/{{Xenogears}}'', many islands and whole continents of the world are missing from maps and unknown by most of the world's inhabitants, who have actually [[LaserGuidedAmnesia been programmed not to notice them]] through an [[AppliedPhlebotinum infection]] called -the Limiter-. After the Limiter is lifted between disc one and disc two, disc two conveniently has a much more featured world map with lands the TrueCompanions have not yet explored. It turns out that the missing lands were places that [[TheEmpire Solaris]] decreed that the planet's inhabitants should forget.
** Halfway correct. Those continents/islands aren't visible because until the middle of the game, they weren't even on the same physical plane as the landmasses that the player is exploring. After the destruction of a certain dimensional generator, the space time barrier separating those landmasses that were 'on the other side' are now accessible. Note that an individual/ships can still pass from one 'plane' to the other with the proper technology; this is offhand referenced a few times throughout the game.

* ''VideoGame/DragonQuestVIII'' has one where you go to the dark world.
** In fact, every ''VideoGame/DragonQuest'' game from ''VideoGame/DragonQuestIII'' onward has one.
** Technically, in ''VideoGame/DragonQuestIII'', you ''start'' in the lost world.
** ''VideoGame/DragonQuestVII'' has all but one island of the world be lost.
* The ''VideoGame/LostPlanet'' series takes place on a literal LostWorld, populated by giant creatures and hidden treasures.
* ''VideoGame/ReturnToMysteriousIsland'' and its sequal play this fairly straight, the second game moreso than the first.
* The Lost City of Z from ''VideoGame/{{Conduit 2}}''.
* ''VideoGame/DonkeyKongCountry'':
** ''VideoGame/DonkeyKongCountry2DiddysKongQuest'' has a Lost World area that is filled with several types of fauna and it isn't found anywhere else on the island. K. Rool is found in an ancient temple of sorts and defeating him sends him flying into the center of the light the temple is radiating, causing the Lost World to implode and sink the island.
** ''VideoGame/DonkeyKongCountry3DixieKongsDoubleTrouble'' has a lost world hidden in an island that is underwater and rises when you reveal it. However, the environment is nothing more than a mountainside with barren forests and a lake.
* In ''VideoGame/TheElderScrollsVSkyrim'', Blackreach. An absolutely vast underground cavern, rich with life found nowhere else in Skyrim, and completely unknown to the world at large. Only a handful of adventurers have discovered it in recent history, and none left alive. In fact, at the beginning of the game, its only three known entrances are sealed off. Discovering it is a particularly [[SceneryPorn beautiful]] part of the main questline.

* ''The Diamond as Big as the Ritz'' by Creator/FScottFitzgerald is all about an isolated pocket of fantastic wealth hidden in Montana. It's been successfully hidden by its wealthy, urbane, and autocratic owners for generations -- but by the time of the story airplane overflight becomes a problem...

* The Hy-yi-yi islands, home of the [[http://en.wikipedia.org/wiki/Snouters Snouters,]] are a Lost World without the ruins. Lots of goofy-looking critters, but for once they're not trying to kill you.
* In the Chinese fable ''The Peach Blossom Spring'' under the pen of [[http://en.wikipedia.org/wiki/Tao_Qian Tao Qian]] (Tao Yuanmíng, c365-427 AD), a fisherman stumbles upon a secluded Utopian village. The friendly villagers explain that their ancestors were driven to seclusion by political strife centuries ago, and have since lost contact with the outside world. The fisherman leaves a few days later, having been requested to keep his adventure a secret. Despite having marked his way out, he never finds the place again.

* Jane Gaskell's ''Literature/{{Atlan}}'' series centers on the adventures of a displaced princess exploring a civilized prehistoric world "before the continents had changed." The first novel, ''The Serpent'', is primarily a JungleOpera; its immediate sequel, ''The Dragon'', ends with the heroine entering Atlantis (or Atlan, as the saga calls it); the third, ''Atlan'', picks up when she becomes empress of the continent. The fourth book, ''The City'', is another JungleOpera, and the final book, ''Some Summer Lands'', explores the last days of the dying continent of Atlan. The first two novels even include a bibliography of (in some cases, discredited) research materials, primarily focusing on prehistoric life.

* The ''Literature/AlcatrazSeries'' of books takes this trope UpToEleven: something like half the Earth's surface is made up of {{Lost World}}s called the Free Kingdoms where all sorts of magical and nonsensical things exist. They only go unnoticed because almost all the world's books, maps, and other sources of information are controlled by [[MilkmanConspiracy an ancient conspiracy of Evil Librarians]] who [[TheMasquerade don't want you to learn the truth]].
* There are two such places in Steve Alten's ''Literature/{{Meg}}'' series. The first one is the Marianas Trench, which is where the titular Megalodons are found. It's [[DownplayedTrope downplayed]], as people already knew of its existence, it just contained a prehistoric creature or two. Playing it much more straight is the Panthalassa sea in the sequel, ''Hell's Aquarium''. It's a primordial sea contained under a rock ceiling at the bottom of the Pacific ocean, and is home to an abundance of ancient sea creatures which have formed a comfortable food chain.
* The underground empire of K'n-yan in Hazel Heald's short story "The Mound" (revised, if not entirely ghost-written, by Creator/HPLovecraft).
* The ''Literature/{{Tunnels}}'' series has the Garden of the Second Sun, where it is theorized that many stages of evolution missing from the fossil record took place. It's also based heavily off of [[ThoseWackyNazis Nazi theories about a hollow earth;]] see the entry in Mythology below.
* DimeNovel hero Literature/NickCarter runs into a lost civilization of Old Norse speaking Amazons in Bolivia.
* [[Literature/CharlieAndTheChocolateFactory Willy Wonka]] discovered the Oompa-Loompa tribe that became his secret workforce in one of these, which overlaps with a HungryJungle. In the pre-{{Bowdlerised}} original text of ''Charlie and the Chocolate Factory'' it was somewhere in DarkestAfrica (these Oompa-Loompas were specifically black pygmies), while later editions and all adaptations change it to the country of Loompaland, which even the geography teacher in the Golden Ticket tour group has never heard of.
* ''Literature/KnownSpace'': As the name implies, Known Space is a 65 light-years bubble in space surrounding Earth where the events of Creator/LarryNiven's eponymous saga occurred. The area refers only to humanity's area of known space, other more advance races have much more extended areas and some adventures happen with humans (and sometimes alien companions) venturing outside Known Space.
* ''Literature/{{Dune}}'': The Known Universe is used by Creator/FrankHerbert to refer to the known areas of space inhabited by humans in an AbsentAliens setting. TheEmperor of the Imperium holds the title of Emperor of the Known Universe, the exact extent is never explain but Herbert refers to it as a "multi-galactic empire", yet when GodEmperor Leto II sees that humanity had stagnate, he arrenges for The Scattering to happen upon his death literally making humanity go out of its comfort zone and explored the rest of the unknown universe.

%%* ''Series/GilligansIsland''
%%* The ''Series/LandOfTheLost''

* A 1999-2002 series based on the titular story was called ''Series/SirArthurConanDoylesTheLostWorld''.
* ''Series/{{The Lost World|2001}}'' was also adapted as an A&E miniseries, in association with the ''Series/WalkingWithDinosaurs'' guys, starring Bob Hoskins, James Fox, and Peter Falk.

* Creator/KarelZeman's ''Journey to the Beginning of Time'', a Czech film that was syndicated to American TV, most notably on ''WesternAnimation/GarfieldGooseAndFriends''.
* The ''Danger Island'' segment from ''WesternAnimation/TheBananaSplits''.

* Kinkao in ''Series/PairOfKings''.
* The ''Series/Danger5'' episode "Lizard Soldiers of the Third Reich" has [[MadDoctor Joseph Mengele]] performing sinister experiments in a Lost World tropical plateau [[MysteriousAntarctica in Antarctica]] where dinosaurs, dinosaur-men, jazz-loving ape-men, and NubileSavage women coexist. After Danger 5 arrives there, we receive a [[{{Technobabble}} ludicrously nonsensical explanation]] for how the plateau has been isolated for 65 million years.
* In ''Series/BabylonFive'' the entire Milky Way seems to be more or less known, but leaving the Milky Way or, as it's called "going over the Rim" is as mysterious as stepping into AnotherDimension to the point that only the more advanced life forms (up to the level of EnergyBeings) dare do it.
* In ''Series/{{Farscape}}'' the Uncharted Territories (where most of the series takes place) are mentioned as the area outside the properly explored Galaxy and are considered lawless and dangerous.
* In ''Series/LostInSpace'' well, the reason they are lost is precisely because after a failed attempt by [[TokenEvilTeammate Dr. Smith]] to destroy the ship in a terrorist-endorsed sabotage he instead got unconscious and caused the ship to derailed (due to his extra weight) from its route out of the areas known to Earth (which are pretty small to begin with).
* In ''Series/{{Firefly}}'' the outer worlds in the edge of TheVerse (a groups of relatively close star systems, as the show has no FasterThanLightTravel) are basically this. Aside from abusive warlords, oligarchs and criminals, the most dangerous thing are [[TechnicallyLivingZombie cannibalistic homicidal maniacs known as Reavers]] who are said to [[GoMadFromTheRevelation going mad]] after they went outside the Galactic rim into the "Abyss" of space. Although the truth is that [[spoiler:they're an experiment GoingHorriblyWorng]].
* In ''Franchise/StarTrek''
** In ''Series/StarTrekTheOriginalSeries'' and the {{prequel}} ''Series/StarTrekEnterprise'', most of what is called the Alpha Quadrant is still this.
** In ''Series/StarTrekTheNextGeneration'': the Alpha and its neighboring Beta Quadrants already mostly explored and mostly charted by TheFederation and neighbors, but still some undiscovered pockets of space became Lost Worlds for the main characters.
** The main plots of ''Series/StarTrekDeepSpaceNine'' and ''Series/StarTrekVoyager'' is the exploration of the other two unknown quadrants, the Gamma and Delta respectively. In the first case thanks to a newly discovered stable wormhole, in the second due to the ship getting lost in there. Of course for the natives of those quadrants is the other way around.

* The Franchise/MarvelUniverse distills this trope into a place known as the "Savage Land." It is a tropical jungle ''in the middle of [[MysteriousAntarctica Antarctica]]'' filled with strange creatures, prehistoric beasts, warrior tribes, incredible civilizations and other great pulpy stuff.
** It was in fact created by aliens.

* ''ComicBook/{{Cavewoman}}'' is supposedly set in the late Cretaceous (with the [[JunglePrincess main character]] having arrived there by time travel) but everything can be found in the primal jungle from StockDinosaurs to giant snakes, [[FrazettaMan hominids]], [[BigfootSasquatchAndYeti yetis]] and... [[AllTrollsAreDifferent trolls]]. Plus, one of the issues is named "Pangaian Sea".
* Marvel similarly had a dinosaur-inhabited island which Skull the Slayer tried to civilize while simultaneously fighting off an AlienInvasion.

* Likewise, Monster Island is the home of the Mole Man, a frequent foe of the ComicBook/FantasticFour. Its location seems to fluctuate between the Bermuda Triangle and just off the coast of Japan, depending on writers' whims.

* The ''ComicBook/{{Turok}}'' comic book series which had a pre-Columbian Native American and his younger brother Andar who enter a lost valley and get trapped in it. They call the dinosaurs which they encounter "Honkers".
** The later Creator/ValiantComics run and the [[VideoGame/{{Turok}} video games]] {{retcon}}ned it into being AnotherDimension called the Lost Lands, and promptly threw a ton of other things into said lands such as robots, aliens, and demons.

* ''ComicBook/DonaldDuck'' has used this trope ''so'' many times. Usually when Scrooge dragged Donald and his nephews along to search for treasures.
* ''Franka'' finds one in a crater on a Phillipine island.
* Atlantis from "The Atlantis Enigma" in ''ComicBook/BlakeAndMortimer''. An empire created before recorded history, it was destroyed (along with much of the Earth's surface) by a falling meteor and the ensuing tidal waves; the survivors eventually build a new empire in vast underground caverns under the Atlantic, which is what Blake and Mortimer discover. They've progressed to the point of becoming an AdvancedAncientAcropolis, mastering anti-gravity technology, laser weaponry, and space travel, among other things.

* ''WesternAnimation/IceAge3DawnOfTheDinosaurs'' uses one to fit dinosaurs into the post-extinction ice age: the dinosaurs survived in an underground lost world.
* ''Disney/AtlantisTheLostEmpire'' has the titular Atlantis, whose core sank beneath the earth millennia ago in a last-ditch effort to save Atlantean civilization from a cataclysm they unlashed and which has lingered on to the modern day in a hidden, fertile cavern deep BeneathTheEarth.

* Doyle's ''Literature/TheLostWorld1912'' was adapted as [[Film/TheLostWorld a silent film in 1925]], with effects by Willis O'Brien, who also worked on ''Film/KingKong1933''. The film was also adapted in 1960 (with [[SpecialEffectsFailure Giant Lizards in Makeup]] playing Dinosaurs), 1992 (with its own sequel--with Handpuppet Dinosaurs) and 1998 (pilot for the above-mentioned TV series).
* '50s BMovie and ''Series/MysteryScienceTheater3000'' feature ''Film/LostContinent'', starring [[Series/Batman1966 Cesar Romero]]. [[LeaveTheCameraRunning And it sure took some finding.]]
* The ''Franchise/JurassicPark'' films (a man-made example). The first sequel is actually titled ''Film/TheLostWorldJurassicPark'' and its plot borrows a lot from Conan Doyle's novel. Also subverted by this series. Both islands can be found on maps, and Isla Sorna is accessible by boat. The islands are explicitly made that way. They were normal tropical islands until dinosaur theme parks and a dinosaur breeding facility were built on them. They were only "lost" after the project was abandoned/dinosaurs ate and killed everything.

* Lagos Island is a fictional island off the coast of Japan. It's subverted in that it can be accessed via plane or boat, but people generally don't live there due to the population of large carnivorous dinosaurs. [[FromBadToWorse Oh, and the island was hit by nuclear radiation]] [[Franchise/{{Godzilla}} mutating said dinosaurs into city-destroying monstrosities.]]
* The lost world of Aphrodisia (home to the [[LadyLand all-female Lubby-Dubby Tribe]]) in ''Film/CarryOnUpTheJungle''.
* The irradiated lost valley in the Tarahuamare Mountains in ''Film/TheCyclops''.
* In ''Franchise/StarWars'' this area outside of what is referred as the "Known Galaxy" and includes more or less a third of the Star Wars galaxy, the expanded universe explains that the undiscovered area has weird and paranormal occurrences making it difficult to colonize.

* Neverland, from J.M. Barrie's ''Literature/PeterPan''. Subverted in that it's a world created by the dreams and stories of children, so only they can really visit it.

** Caspak (aka Caprona), a Lost World within MysteriousAntarctica, the setting for the novel ''Literature/TheLandThatTimeForgot'' and its sequels.
** ''The Lost Continent'' (originally known as ''Literature/BeyondThirty'') -- the eponymous continent is Europe, in an AlternateHistory in which UsefulNotes/WorldWarI never ended because eventually no organized government was left to make peace. The United States never entered the war, and in fact made laws forbidding any ship to cross certain lines of longitude (hence the original title).
* ''Literature/TheLostWorld1912'' by Sir Arthur Conan Doyle is the TropeNamer.
* Creator/RobertEHoward's SolomonKane encountered some of these in DarkestAfrica. In particular, "The Moon of Skulls" featured a lost city that is all that remains of a once-vast empire which began as an outpost of {{Atlantis}}.

* ''Literature/{{Dinotopia}}'' plays this trope about as straight as possible.
* Franchise/DocSavage encountered several {{Lost World}}s, the most significant being the lost Mayan kingdom that provided him with the gold necessary to carry on his crusade. Several of these {{Lost World}}s are also [[CityOfGold Cities Of Gold]].
* ''The Diamond as Big as the Ritz'' by F. Scott Fitzgerald is all about an isolated pocket of fantastic wealth hidden in Montana. It's been successfully hidden by its wealthy, urbane, and autocratic owners for generations -- but by the time of the story airplane overflight becomes a problem...
* [[DeathWorld Henders Island]] from ''Literature/{{Fragment}}'' plays this so literally it hurts.

** ''The Lost Continent'' (originally known as ''Beyond Thirty'') -- the titular continent is Europe, in an AlternateHistory in which UsefulNotes/WorldWarI never ended because eventually no organized government was left to make peace. The United States never entered the war, and in fact made laws forbidding any ship to cross certain lines of longitude (hence the original title).

* In ''Literature/BeyondThirty'', a group of shipwrecked American mariners in the 22nd century explore the savage lost continent of Europe. In this future history (the story was published in 1915), World War I never ended because eventually no organized government was left to make peace. The United States never entered the war, and in fact made laws forbidding any ship to cross certain lines of longitude (hence the title).