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Subterranean fiction is a subgenre of speculative fiction, science fiction, or fantasy which focuses on fictional underground settings, sometimes at the center of the Earth or otherwise deep below the surface. The genre is based on, and has in turn influenced, the Hollow Earth theory.
The earliest works in the genre were Enlightenment-era philosophical or allegorical works, in which the underground setting was often largely incidental. In the late 19th century, however, more pseudoscientific or proto-science-fictional motifs gained prevalence. Common themes have included a depiction of the underground world as more primitive than the surface, either culturally, technologically or biologically, or in some combination thereof. The former cases usually see the setting used as a venue for sword-and-sorcery fiction, while the latter often features cryptids or creatures extinct on the surface, such as dinosaurs or archaic humans. A less frequent theme has the underground world much more technologically advanced than the surface one, typically either as the refugium of a lost civilization, or (more rarely) as a secret base for space aliens.
Literature
Map of the Interior World, from The Goddess of Atvatabar (1892)
In Ludvig Holberg's 1741 novel Nicolai Klimii iter subterraneum (Niels Klim's Underground Travels), Nicolai Klim falls through a cave while spelunking and spends several years living on both a smaller globe within and the inside of the outer shell.
Giacomo Casanova's 1788 Icosaméron is a 5-volume, 1,800-page story of a brother and sister who fall into the Earth and discover the subterranean utopia of the Mégamicres, a race of multicolored, hermaphroditic dwarfs.
An early science-fiction work called Symzonia: A Voyage of Discovery by a "Captain Adam Seaborn" appeared in print in 1820. In the story, Captain Seaborn leads a group of travelers into the concave inner surface of the Earth. There, they discover an inner continent, which they name Symzonia after John Cleves Symmes, Jr. The story obviously reflected the ideas of Symmes, and some have claimed Symmes as the real author. Other researchers say it deliberately satirized Symmes's ideas, and think they have identified the author as an early American author named Nathaniel Ames (see Lang, Hans-Joachim and Benjamin Lease. "The Authorship of Symzonia: The Case for Nathanial Ames" New England Quarterly, June 1975, page 241–252).
Faddei Bulgarin's short satirical tale "Improbable Tall-Tale, or Journey to the Center of the Earth" (1825) describes three underworld countries: Ignorantia (populated by spiders), Beastland (populated by apes), and Lightonia (populated by humans, with a capital called Utopia).
Although it is often suggested that Jules Verne used the idea of a partially hollow Earth in his 1864 novel Journey to the Center of the Earth, his characters actually descend only 87 miles beneath the surface, where they find an underground sea occupying a cavern roughly the size of Europe. There is no indication in the novel that Verne intended to suggest that the Earth was in any way hollow, partially or otherwise.
Alexandre Saint-Yves d'Alveydre's "Mission de l'Inde en Europe" was published in 1886 as a "true" story about Agartha. He withdrew it from the print and it was released again by Gérard Encausse in 1910.
John O. Greene's utopia The Ke Whonkus People (1890) describes an 11,000 year-old subterranean civilization at the North Pole, circa 1886, with a "fine climate" and "highly civilized people."
William R. Bradshaw's science fiction novel The Goddess of Atvatabar (1892) is a utopian fantasy set within the hollow Earth.
Will N. Harben's Land of the Changing Sun (1894) is a utopian fantasy set within a 100-mile wide cavern found below the Atlantic Ocean 200 years prior and settled. The settlers found the atmosphere very rejuvenating, and also build an artificial changing sun to light their world. Two balloonists, an American and an Englishman, discover this world.
In the sociologist Gabriel Tarde's only literary work, Underground Man (1896) (original French title Fragments d'Histoire Future), Humanity escapes a second apocalyptic ice age by delving under the earth and reforming society with Art as its central value.
Charles Willing Beale's 1899 novel, The Secret of the Earth tells of the adventure of two brothers who build an anti-gravity airship and travel to the hollow Earth. There they find several lost races, and learn that mankind originated in the hollow Earth, but the unruly types were exiled from the hollow Earth. They then exit via the South Pole opening and crash on an island in the South Pacific, from which they send off a log of their adventures which forms the novel.
In NEQUA or The Problem of the Ages a visit in a sailing ship is made to Altruria, a society inside the earth. This feminist utopian science fiction novel was published in 1900 in Topeka Kansas. Jack Adams listed as the author, was a pseudonym for A. O. Grigsby and Mary P. Lowe, both newspaper publishers.
Willis George Emerson's science-fiction novel The Smoky God (1908) recounts the adventures of one Olaf Jansen who traveled into the interior and found an advanced civilization.
Edgar Rice Burroughs wrote adventure stories (beginning with At the Earth's Core in 1914) set in the inner world of Pellucidar, including at one point a visit from his character Tarzan. Burroughs's Pellucidar has oceans on the outer surface corresponding to continents on the inner surface and vice versa. Pellucidar is lit by a miniature sun suspended at the center of the hollow sphere, so it is perpetually overhead wherever one is in Pellucidar. The sole exception is the region directly under a tiny geostationary moon of the internal sun; that region as a result is under a perpetual eclipse and is known as the Land of Awful Shadow. This moon has its own plant life and (presumably) animal life and hence either has its own atmosphere or shares that of Pellucidar.
The Russian geologist Vladimir Obruchev uses the concept of the hollow Earth in his 1915 scientific novel Plutonia to take the reader through various geological epochs.
The World Below by British science fiction author S. Fowler Wright was a major novel of 1929, and important in the history of science-fiction as a bridge between the scientific romance and the pulp era. It is set in the far-future in which Earth's dominant race lives almost entirely underground.
Morgo the Mighty by Sean O'Larkin was serialized in The Popular Magazine in 1930. It featured the adventures of a Tarzanesque character in a network of giant caverns beneath the Himalayas. The caves are ruled by a cowled magician and populated by primitive men, giant intelligent bats, giant warring ants and giant killer chickens.
The novel The Secret People (1935) by John Wyndham features prisoners held captive in a labyrinth of caves by an ancient race of pygmies dwelling beneath the Sahara desert.
In the Middle-earth books by J.R.R. Tolkien, the kingdom of Angband and its predecessor Utumno are deep underground, under mountains called Ered Engrin; they are home to Orcs, monsters and Morgoth the Dark Lord. Also, the Dwarves and even elves live underground – the underground realms of Moria and Erebor and cities like Nargothrond and Menegroth play a major role in the stories.
While investigating a haunted mound in Oklahoma, the protagonist of H. P. Lovecraft's novella The Mound discovers a Spanish explorer's account of his travels in a subterranean civilization named K’nyan.
Richard Sharpe Shaver's The Shaver Mystery stories are about ancient civilizations still living in caverns beneath the Earth surface
Into a Strange Lost World (1952), a novel for children by Richard Hough (pen name: Bruce Carter), tells the story of two airmen who are shot down in the Second World War and descend into an underground world.
The End of the Tunnel (aka The Cave of Cornelius) (1959), by Paul Capon. Four boys in England get trapped in a cave by a landslide, and by following the cave, they encounter a forgotten civilization.
Dark Universe (1961) by Daniel F. Galouye. A post-apocalyptic science fiction novel where two clans live deep underground and are descendants from humans who escaped an old war.
City of the First Time (1975) by G.J. Barrett. British survivors of an atomic holocaust venture downward into the Earth through a series of caves and encounter two other races, survivals of previous extinctions.
Visages Immobiles (1983) by Raymond Abellio. Having discovered that New York was built on top of a massive hollow cavity, an architect devises a plan to build an underground city below Manhattan. The underground setting then becomes the scenario of the apocalyptic battle between a clairvoyant and an international terrorist.
A Hollow Earth featured in the children's Choose Your Own Adventure novel The Underground Kingdom (1983).
The history of the Hollow Earth theory is explored in Umberto Eco's 1988 novel Foucault's Pendulum, alongside a wide range of other pseudo-scientific and conspiracy theories.
In Jeff Long's 1999 novel The Descent and its 2007 sequel Deeper, a vast labyrinth of tunnels and passages underlying the Earth is inhabited by a brutal species of once-civilized but now degenerate hominid, Homo Hadalis.
The 2000 novel Abduction by Robin Cook includes the concept of a third world under the sea called "Interterra."
Eoin Colfer's Artemis Fowl series (2001–2012) focuses on crimes committed by or against the fairy-folk who live beneath the Earth's crust in a technologically advanced society.
Underland (2002) by Mick Farren has the vampire hero Victor Renquist traveling to a hollow Earth populated by Nazi scientists, subjugated proto-scientific lizard people, and a fungus addicted race of sub-vampires.
Tunnels (2005) is the first of a series of books by Roderick Gordon and Brian Williams, taking place in a hollow Earth with an interior sun, in which multiple civilisations exist within and beneath the crust.
Metro 2033 (2005) and Metro 2034 (2009) by Dmitry Glukhovsky are post-nuclear-apocalyptic novels which describe the last remaining humans fighting to survive in the metro system underneath Moscow with the surface being too irradiated for humans to survive.
Against the Day (2006) by Thomas Pynchon makes extensive mention of the Earth's interior as a place to be explored, positing inner-Earth seas. Pynchon's Mason & Dixon (1997) also uses the idea of a Hollow Earth as the planet's final holdout for magic against the calculations of the surface's most eminent men of science.
Neal Shusterman's Downsiders (1999) is a story where a young boy living under New York City in a secret community becomes curious about the topside and adventure ensues.
John Hodgman's 2008 book More Information Than You Require says the hollow interior of the Earth is the home of the subterranean Molemen. In the center of this Hollow Earth is a small, red sun.
The Silo series narrates post-apocalyptic human life in a subterranean city extending one hundred forty-four stories beneath the surface.
Kameron Hurley's 2017 novel The Stars Are Legion takes place on an alien world with various separate underground societies that the protagonist must work her way through on a long journey back to the surface.
The comics series Les Terres Creuses by Belgian comics writers Luc and François Schuiten features several hollow-Earth settings.
The Hellboy Universe features the Hollow Earth as a major part of its mythology. It was first introduced in the 2002 miniseriesB.P.R.D.: Hollow Earth, when the team journeyed into great caverns inside the Earth where they discovered a race of people that had been artificially created by the ancient Hyperboreans.
One adventure of Alan Moore's Pulp-style hero Tom Strong involved a gateway into the Hollow Earth in the Arctic where Nazis had fled after World War Two only to be devoured by its inhabitants. Much of the story is spent discussing many of the varying Hollow Earth concepts mentioned above. (Tom Strong's Terrific Tales #1)
In the 1970s, comic-book artist Mike Grell produced the comic-book Warlord, about a pilot who finds himself in Skartaris, a sword-and-sorcery world reached through an opening at the North Pole. First believed to be the hollow interior of the Earth, Skartaris was later revealed to be a parallel dimension.
Super Dinosaur has shown Earth to be a planet with a planet on the inside.
The webcomicMare Internum follows the adventures of two scientists trapped in the underworld of Mars.
Film
The 1935 serial The Phantom Empire combines a western musical with subterranean plot elements loosely adapted from Bulwer-Lytton's The Coming Race.
The 1951 short feature Superman and the Mole Men postulated a race of little people living inside a hollow Earth. The film was later reconfigured into a two-part TV episode called The Unknown People, with most or all explicit references to "Mole Men" being excised.
The 1951 film Unknown World is the story of a small crew in a drilling vehicle exploring for a refuge from nuclear war, and finding great caverns at tremendous depths.
The 1956 film The Mole People has an introduction by Frank C. Baxter ("Dr. Research") explaining the history of Hollow Earth theories.
The 1960 film The Time Machine is based on the H.G. Wells novel and features underground-dwelling Morlocks.
The 1970 film Beneath the Planet of the Apes is the second film in the Planet of the Apes series and features an underground city inhabited by mutated humans with psychic powers.
The 1971 film THX 1138 is an American science fiction film set in a dystopian future in which the populace lives underground and is controlled through android police officers and mandatory use of drugs that suppress emotion, including outlawed sexual desire.
The 1973 film Godzilla vs. Megalon involves the Seatopians, an underground civilization that sends Megalon to destroy the surface world in response to earthquakes caused by underground nuclear testing damaging their kingdom.
The 1984 film What Waits Below depicts the discovery of a lost race of albino-skinned beings.
The 1999 film "The Matrix" features the underground refuge of Zion.
The 2001 animated film Atlantis: The Lost Empire, has the protagonists discovering the survived ancient civilization of Atlantis in the depths of the Earth.
The 2003 film The Core in which a team has the mission to drill to the center of the Earth in order to restart the rotation of the Earth's core.
The 2004 Japanese horror film Marebito, directed by Takashi Shimizu, references the Hollow Earth hypothesis.
The 2005 film The Island is an American science fiction-thriller film directed by Michael Bay, starring Ewan McGregor and Scarlett Johansson.
The 2008 film Journey to the Center of the Earth has the protagonists Professor Trevor Anderson, his nephew Sean Anderson, and a volcanologist's daughter ending up at the Center of the Earth after traversing a mine system. Unlike the book, the "Center of the Earth" is thousands of miles beneath the Earth's surface and is an air pocket surrounded by hot lava causing the location to easily hit 200 degrees during certain volcanic activities above it.
Hollow Earth is a major plot element of the MonsterVerse film franchise. The 2017 film Kong: Skull Island places Skull Island atop an entryway into Hollow Earth that is responsible for its population of giant monsters and plant/animal hybrids. The 2019 film Godzilla: King of the Monsters reveals the existence of a Hollow Earth with portals that Godzilla uses as shortcuts to move faster around the globe. The 2021 film Godzilla vs. Kong features an expedition into Hollow Earth to harness a mysterious energy source and find Kong's ancestral home. Due to a strong reverse-gravitational effect, Apex Cybernetics has developed HEAVs which are specialized crafts able to withstand the pressure exerted by the gravity field.
The 2024 Kurdish feature film from Iraqi Kurdistan, Where Is Gilgamesh?, based on the Epic of Gilgamesh, has the protagonists in search to find a hidden secret written on one of the Tablet of Gilgamesh, one of his search taken him into the depths of the Earth.
The main antagonists of Inhumanoids are giant monsters who originate from a subterranean world, and the protagonists regularly travel underground to battle against them.
The Spider Riders series of books and anime take place in an "Inner World" inhabited by humans, cybernetic battle spiders, and intelligent insects.
The anime series Gurren Lagann is initially set in an underground civilization due to the surface of the world being ruled by Lordgenome.
The Transformers: Cybertron cartoon series features a character, Professor Lucy Suzuki, who believes in the Hollow Earth Theory.
The Japanese anime Gaiking: Legend of Daiku-Maryu has the protagonists spend much of their time in a hollow Earth called Darius, home of an empire of humanoids that are currently amassing a force to invade and conquer the surface world.
The French cartoon Les Mondes Engloutis (known in English as Spartakus and the Sun Beneath the Sea) involves protagonists descending through a maze of caves into a subterranean world of different space and time, inhabited by various peoples.
Sanctuary has a Season 3 storyline that deals with Helen Magnus and her team finding and visiting Hollow Earth.
In Detentionaire, the main antagonist of the series known as "His Eminence" is from a long lost race of ancient reptilian humanoids who retreated beneath the earth and lay dormant for thousands of years.
In Doctor Who Series 5 (2010), episodes 8 and 9 The Hungry Earth and Cold Blood take place in an underground city populated by Silurians, a humanoid reptilian race who have been hibernating for millions of years and want to have their planet back from the "ape descended primitives" who have evolved and taken over (i.e. humankind). The Silurians and their aquatic cousins the Sea Devils also appeared in the original run of Doctor Who - in Doctor Who and the Silurians (1970), The Sea Devils (1972) and Warriors of the Deep (1984).
The animated television series Billy Dilley's Super-Duper Subterranean Summer takes place in an underground world called Subterranea-Tania, which the main characters get trapped due to a science project gone awry.
Games
The interactive fiction computer games in the Zork series (1977-1982) are set in the Great Underground Empire.
The 1992 video game Ultima Underworld: The Stygian Abyss is set in a large cave system that contains the remnants of a failed utopian civilization.
The 1993 video game Mage: The Ascension, the Hollow Earth exists as an alternate reality, but virtually all ways of accessing without magic have ceased to exist in the modern age because people no longer believe the Earth could be hollow.
The 1993 video game series Myst, the D'ni civilization lies in a large cavern under the U.S. state of New Mexico.
The 2000 video game series Avernum, and its predecessor, Exile (1995), the nation is based in a cavern system once used as a penal colony.
The 2001 role-playing video game King's Field IV released in North America as King's Field: the Ancient City takes place predominantly in the Ancient City, an underground domain in the land of Heladin which has been stricken by darkness since their king received a strange idol. The player is tasked with venturing further and further downwards exploring much of the subterranean city in its decay and desolation.
The 2001 real time strategy game Pikmin, features a large cave called the Forest Navel, while being underground there is a single hole at the top to enter. The sequel, Pikmin 2 (2004), has the main characters delving into 14 somewhat varying caverns for treasure, one of which is aptly titled "Subterranean Complex".
The 2002 video game Arx Fatalis, takes place almost entirely in an underground setting.
The 2002 video game Breath of Fire: Dragon Quarter is set entirely in an underground world, where the main characters try to reach the surface.
The 2008 video game Subterranean Animism, the 11th video game in the Touhou Project series, revolves around the main character descending underground into the depths of Hell in order to stop a possible apocalyptic event from occurring.
The 2008 MMO video game, Aion: Tower of Eternity, the world of Atreia used to be a hollow planet with the Tower inside it, connecting the northern and southern hemispheres together, providing light and heat to the creatures living inside of the planet.
The 2009 browser-based game Fallen London, as well as its roguelike spin-off Sunless Sea, are set in an alternate history in which Victorian London is now located a mile beneath the surface, in an enormous cavern colloquially referred to as the "Neath" dominated by a large subterranean ocean.
The 2009 tabletop game, Pathfinder Roleplaying Game's main setting, Golarion, features an extensive underworld known as the Darklands. The deepest region of the Darklands, known as Orv, consists of a series of caverns (referred to as Vaults) roughly the size of surface nations, home to a variety of alien environments, creatures and cultures.
The 2009 video game Dragon Age: Origins features an underground city by the name of Orzammar
The 2011 video game The Elder Scrolls V: Skyrim features an underground city by the name of Blackreach with large glowing mushrooms and a large "sun" hanging from the ceiling, Blackreach connects the Dwemer cities: Alftand, Mzinchaleft, and Raldbthar which are also underground and feature large amounts of Steampunk technology.
The 2011 sandbox video game Minecraft features remnants of forgotten civilizations hidden deep within the earth, such as the Stronghold and the Ancient City. Furthermore, there exists a dimension in the game called the Nether, largely considered to be located below the Overworld. Here, there exist derelict structures such as Bastion Remnants and Nether Fortresses, along with the Piglins, a race of sentient, humanoid pig creatures.
The 2012 MMORPGThe Secret World, the Hollow Earth serves as a central hub allowing the player to travel between the different area of the outer world. In the 2017 reboot, Secret World Legends, it has been redesigned for being the central place for trade, meetup and services.
The 2013 unreleased RPG Deep Down focuses on deep diving into an ancient civilization below the earth to discover its secrets while using powerful abilities and a dynamic lighting system to survive its deep dank depths while also combating terrifying grimdark foes such as an ancient dragon like the one shown in the 2013 Tokyo Game Show Trailer.
The 2015 video game Undertale, the main character falls into the Underground, a subterranean realm which serves as the setting for the game. The Underground is populated with a society of monsters which were banished there by humans.
The 2015 role-playing game Underrail is set in a distant future, where life on Earth's surface has long since been made impossible and the remnants of humanity now dwell in a vast system of metro station-states.
The 2017 Metroidvania game Hollow Knight takes place on Hallownest, a ruined kingdom built inside a vast series of interconnected caverns, presenting lakes, lush caves and forgotten cities, among other various areas.
Japanese psychedelic rock band Far East Family Band named their 1975 debut album Chikyu Kudo Setsu, (Hollow Earth Theory), although the official English title was The Cave Down to Earth. The album's sleeve notes refer to familiar stories of entrances at the north and south poles, and of an ancient civilisation dwelling inside the Earth with connections to UFOs.
The band Bal-Sagoth has, on their album The Chthonic Chronicles (2006), a song about the hollow Earth called "Invocations Beyond the Outer-World Night".
In Coldplay's first full album Parachutes there's a song called "Spies". It may refer to a subterranean location, but the lyrics themselves are ambiguous.
Science Babble, on their album Membrane has a song "Rock Bottom" revolving around hollow Earth theory.
Other celestial bodies
Subsurface fiction may also be set on other planetary bodies:
The most common example of a hollow body other than Earth has historically been a hollow Moon. A breathable interior atmosphere allowed various SF writers to postulate lunar life (including intelligent life) in spite of scientific observations of the uninhabitability of the Lunar surface. The subgenre largely died out following the actual Moon landings.
The console Strategy/RPG series Super Robot Wars features a Hollow Earth world named La Gias.
"World Without Stars", the third volume of the French graphic space novel series Valérian: Spatio-Temporal Agent takes place mainly inside a hollow planet inhabited by a matriarchal and a patriarchal culture continuously at war with each other.
