Subterranean fiction is a subgenre of adventure fiction which focuses on 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 creatures extinct on the surface, such as dinosaurs, hominids or other cryptids. 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 base for space aliens.
- In Dante Alighieri's Divine Comedy poem Inferno, Hell is a vast underground cavern and the narrator travels through the center of the Earth and out the other side.
- 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. It obviously reflected the ideas of John Cleves Symmes, Jr. and some have claimed Symmes as the real author. Some 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).
- Edgar Allan Poe used the idea in his 1838 novel The Narrative of Arthur Gordon Pym of Nantucket. He also touches on it in his short stories "MS. Found in a Bottle" and "The Unparalleled Adventure of One Hans Pfaall."
- Although it is often suggested that Jules Verne used the idea of a partially hollow Earth in his 1864 novel, A 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.
- Lewis Carroll's 1865 novel Alice's Adventures in Wonderland was originally titled Alice's Adventures Under Ground.
- Edward Bulwer-Lytton's 1871 novel The Coming Race was an account of the Vril-ya, an angelic subterranean master race.
- Mary Lane's Mizora (1880–81) combines the hollow-Earth theme with feminism.
- James De Mille's novel A Strange Manuscript Found in a Copper Cylinder, published in 1888 but written prior to the author's death in 1880, depicts a subterranean land with inverted values.
- Pantaletta: A Romance of Sheheland by Mrs. J. Wood (1882)
- George Sand used the idea in her 1884 novel Laura, Voyage dans le Cristal, in which giant crystals could be found in the interior of the Earth.
- Interior World, A Romance of Illustration a New Hypothesis of Terrestrial Organization by Washington L. Tower (1885)
- William R. Bradshaw's science fiction novel The Goddess of Atvatabar (1892) is a utopian fantasy set within the hollow Earth.
- The protofeminist utopia Etidorhpa (1895) by John Uri Lloyd is also set within a hollow Earth.
- The concept was mentioned in Wardon Allan Curtis's 1899 short story "The Monster of Lake LaMetrie."
- An underground Nome Kingdom is featured in several of the Oz books by L. Frank Baum, notably the Ozma of Oz (1907), Dorothy and the Wizard in Oz (1908) and Tik-Tok of Oz (1914).
- 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.
- A deliberately tunneled-out Earth occurs in Charles R. Tanner 1930's SF short story "Tumithak of the Corridors".
- Morgo the Mighty by Sean O'Larkin was serialized in The Popular Magazine in 1930. It featured the adventures of a Tarzan like 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.
- Tam, Son of the Tiger by Otis Adelbert Kline from 1931 features the adventures of Tam (another Tarzan like character) in a subterranean world beneath Asia.
- C. S. Lewis's 1953 novel The Silver Chair (part of The Chronicles of Narnia) takes place partly in Underland, a subterranean kingdom plotting to conquer Narnia. At one point, the Lady of the Green Kirtle attempts to brainwash the protagonists into believing that the world above ground does not exist.
- The Third Eye (1956) by Tuesday Lobsang Rampa mentions contact with advanced beings living in the center of the Earth.
- 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 to 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.
- 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.
- Rudy Rucker's novel The Hollow Earth appeared in 1990, and features Edgar Allan Poe and his ideas. Rucker claims in an afterword to have transcribed the novel from a manuscript in the University of Virginia library; the call number given is that of a copy of Symzonia.
- The novel Indiana Jones and the Hollow Earth by Max McCoy (1997) expands on the legend of an advanced civilization in the Earth's interior.
- The short story "Black as the Pit, From Pole to Pole" by Howard Waldrop and Steven Utley continues the journey of Frankenstein's creature through a hollow Earth.
- 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."
- 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.
- The City of Ember (2003) and its sequels by Jeanne DuPrau describe a city built underground to survive a nuclear holocaust.
- 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 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.
- In Geraldine McCaughrean's The White Darkness (2007), the characters undertake a journey to find a hole into the hollow Earth.
- John Hodgman's 2008 book More Information Than You Require says the hollow interior of the Earth as the home of the subterranean Molemen. In the center of this Hollow Earth is a small, red sun.
- The Underland Chronicles by Suzanne Collins tells the story of a war between the humans and the rats in a location under New York City called the Underland.
- The Battle of the Labyrinth, the fourth book in Rick Riordan's Percy Jackson and the Olympians series, revolves around the protagonists' attempts to navigate the Labyrinth, a confusing, supernatural maze under the United States.
- Eoin Colfer's series of Artemis Fowl books focus on crimes committed by or against the Fairy-folk who live beneath the earth's crust in a technologically advanced society.
- Tunnels, a series of books by Roderick Gordon and Brian Williams, takes place in a hollow Earth with an interior sun, in which multiple civilisations exist within and beneath the crust.
- The Dark Elf Trilogy, by R.A. Salvatore was the first of the Forgotten Realms books to describe the underground world of the Dark Elves called The Underdark. This greatly helped popularize underground settings in fantasy RPGs.
- A Scrooge McDuck comic book story by Carl Barks called Land Beneath the Ground! (1956) describes an underground world populated by humanoid creatures who create earthquakes.
- The comics series Les Terres Creuses by Belgian comics writers Luc and François Schuiten features several hollow-Earth settings.
- Trade paperback #1 B.P.R.D.: Hollow Earth and Other Stories of the comic book series Bureau for Paranormal Research and Defense by Mike Mignola, creator of Hellboy, contains the short story Hollow Earth, where the team journeys into great caverns inside the Earth inhabited by Hyperborean people and fantastic machines.
- 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.
- The Marvel Comics features several underground empires in Subterranea ruled by villains like the Mole Man or Tyrannus.
- The webcomic Overcompensating referenced Hollow Earth theories in an August 2006 strip.
- Super Dinosaur has shown Earth to be a planet with a planet on the inside.
- The 1935 serial The Phantom Empire combines a western musical with subterranean plot elements loosely adapted from Bulwer-Lytton's The Coming Race.
- The 1956 film The Mole People has an introduction by Frank C. Baxter ("Dr. Research") explaining the history of Hollow Earth theories.
- The 1959 film Journey to the Center of the Earth is probably the most well known adaptation of Verne's novel.
- The 1973 film Godzilla vs. Megalon involves the seatopians.
- The 1976 film At the Earth's Core is based on Burroughs' novel.
- The 1984 film What Waits Below depicts the discovery of a lost race of albino-skinned beings.
- The 2004 Japanese horror film Marebito, directed by Takashi Shimizu, references the Hollow Earth hypothesis.
- The 2008 film Journey to the Center of the Earth, as well as the similar film Journey to Middle Earth.
- The 2008 film "City of Ember" is the survival story of a fantasy underground city.
- The 2009 film Ice Age: Dawn of the Dinosaurs features an underground world where dinosaurs have survived into the Holocene.
- In the Tiny Toon Adventures episode "Journey to the Center of Acme Acres", a series of earthquakes shake up the city, causing Plucky and Hamton to fall into a crater in the ground. They fall for hours before finally reaching the center, which is hollow.
- The Spider Riders series of books and anime take place in an "Inner World" inhabited by humans and intelligent insects.
- The anime series Gurren Lagann is initially set in an underground civilization.
- 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 underground 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.
- Series 5, episode 8 and 9 in the British series Doctor Who takes place in an underground city populated by lizardmen who wants to have their earth back.
- The video game Final Fantasy IV for the Super Nintendo Entertainment System (Released as "Final Fantasy II" in the United States) features a subterranean world that is inhabited by dwarves.
- The video game Terranigma for the Super Nintendo Entertainment System features both a hollow and normal Earth.
- A pulp roleplaying game, Hollow Earth Expedition.
- The Dungeons & Dragons role-playing game's Mystara campaign setting included a Hollow World expansion, featured in the Hollow World Campaign Set.
- In 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.
- In 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 video game Dragon Age: Origins features a subterranean city, along with other subterranean caves.
- Arx Fatalis takes place almost entirely in an underground setting.
- 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".
- Sunn O))) on their album Monoliths & Dimensions has a song called Aghartha.
- 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.
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 sub-genre largely died out following the actual Moon landings.
- The console Strategy/RPG series Super Robot Wars features a Hollow Earth world named La Gias.
- The role-playing video game Septerra Core takes place on an eponymous world with seven separate layers, similar to the theory of Edmund Halley.
- The PC Adventure game Torin's Passage features a depiction of the hollow fictional planet Strata, similar to the one described by Edmund Halley.
- The planet Naboo in Star Wars has a "hollow core," but it is filled with water.
- In the Star Trek: The Original Series episode "For the World Is Hollow and I Have Touched the Sky", there is a hollow, artificially created, planet-shaped spaceship whose inhabitants falsely believe that they are living on the surface of a planet.
See also 
- Jules Verne, Journey to the Center of the Earth, (Oxford, 1992) William Butcher translation.
- Standish, David (2006), Hollow earth: the long and curious history of imagining strange lands, fantastical creatures, advanced civilizations, and marvelous machines below the earth's surface, Da Capo Press, ISBN 0-306-81373-4
- Reported in Julian Cope's Japrocksampler, pp. 246–7.