Tunnel Network

A Tunnel Network is any collection of buildings that link to a large underground catacomb of tunnels that allow for stealthy travel around a locale. Sometimes these might have been built by dedicated criminal networks for the sake of transporting things covertly from place to place. Sometimes they're built during times of war to allow a way to sneak past, or sneak up on, enemies. Less common uses of Tunnel Networks include avoiding a dangerous climate aboveground, or to serve as the equivalent of roads for those who live Beneath the Earth. Yet another use would be that shifty government laboratory that is not only underground but randomly dusty.

In the competitive gaming world, this means cheap near instant transport between any two points. A shrewd gamer will be able to take advantage of this and employ what is called tunnel popping, quickly transferring units in and out of tunnels, and all around the map to a devastating effect.

In other media, while not allowing for something as cheap as delivering a Zerg Rush to your doorstep, can allow for secretive travel between locations hiding both literal and logistical foot prints.

For its high tech equivalent, see Portal Network. Occasionally related to Absurdly Spacious Sewer and Pipe Maze. A Secret Underground Passage sometimes leads to this, but is technically a different trope. This refers specifically to a massive underground network of tunnels, not a single tunnel used for a singular purpose. Be alert in the event the network is home to a Beast in the Maze.

---

Examples:

Anime & Manga

• In Fullmetal Alchemist, the Ed and Al discover one of these underneath Amestris, though they soon discover that Pride keeps all unauthorized people out if he doesn't kill them outright. The purpose of these tunnels is as a massive, countrywide alchemic transmutation circle designed to rip the souls out of every human in the country once finished.
• Nadia: The Secret of Blue Water: Ancient Atlanteans dug tunnels across the world and continents; they ended to be used by the Nautilus crew after their ship was destroyed by Gargogyle.
• In One Piece, Ms. Merry Christmas creates impromptu linked paths underground with her Fast Tunnelling ability. She makes extensive use of these networks to ambush her opponents and keep them guessing where she'll be next. Chopper uses the fact that they're connected against her by filling the tunnels with bombs, knowing no matter where she is, the bombs' explosions will reach her.

Comic Books

• Gotham's Absurdly Spacious Sewer, the old steam tunnels, both the used and disused subway lines as well as a number of other unused underground tunnels, mostly those which were never completed for their original function, combine to give Batman, his allies and some of his enemies a convenient way to get around Gotham unseen. The Batcave even connects to a never used section of subway line.
• Juice Squeezers: Beneath the town of Weeville, California is a vast network of underground tunnels created by the Big Creepy-Crawlies that live there and regularly menace the community. They're only big enough that kids can fit in them, hence why the titular team are all preteens.
• Wonder Woman Vol 1: Hypnota's villain lair is a whole series of interconnected Secret Underground Passages, which makes it so that even if someone does find her lair they're likely to get lost once they get in.

Films — Animated

• In Kirikou and the Sorceress, Kirikou is small enough to use a network of animal burrows beneath the surface to stealthily cross the domain of Karaba the witch without being detected by her lookout fetish, and digs his path further with his father's dagger whenever necessary. How he is able to see anything down there however is left unexplained.
• In Madagascar, the penguins are introduced digging a tunnel to escape from the zoo. In the Spin-Off series The Penguins of Madagascar, it's revealed that they have a network of 15 escape tunnels, some of which lead to their command center.
• The Geonosians in Star Wars: The Clone Wars.

Films — Live-Action

• The gopher in Caddyshack has something like this.
• Kaamelott: Premier Volet: a resistance movement to Lancelot's tyranny led by Perceval, Karadoc and later Merlin dig tunnels underneath Kaamelott, just for the sake of it at first. The fact that their refusal to map the tunnels leads to them digging in circles (until Merlin brings them maps) is only an irrelevant detail. A good use for the tunnels is found during the Final Battle, that said.
• In Real Genius, steam tunnels are how Lazlo gets around Pacific Tech unseen — they are modeled on the very real tunnels beneath Caltech.
• Bane and his mooks employ the Gotham sewer network in The Dark Knight Rises as a lair and a means of transportation. The same tunnels are used to trap the police force later.

Literature

• Robert A. Heinlein's Starship Troopers features bug colonies had vast underground tunnel networks that allowed them to pop up and attack the MI on the surface of the planet.
• In the Deryni series, Castle Coroth (Alaric Morgan's stronghold) has a network of secret passages in its walls that (according to Morgan) can be used to get almost anywhere in the castle without being seen. When Morgan, Kelson, and a few others slip into the castle to take it back from Warin de Grey, Morgan uses these passages to get into his private quarters without being seen. Rhemuth Castle, where King Brion and his son Kelson live, is also honeycombed with secret passages.
• In Good Omens, there's a sequence where various New Age beliefs start coming true, one of which is the conspiracy theory that the Secret Masters of the World live in a cave beneath Tibet and travel around the world through an extensive tunnel system. This results in things like gardening programs offering tips on what to do if a nosy Tibetan monk pops up in the middle of your flower bed.
• In Pyrates, there's a large network of tunnels and caves underneath New York City, used both by homeless people simply to survive, and by smugglers and thieves.
• In The Riftwar Cycle, the city of Krondor has an Absurdly Spacious Sewer belowground that is known as the "Thieves' Highway" because the Mockers (the resident Thieves' Guild) uses them to get around and move smuggled and stolen goods. Castle Krondor, where the Prince of Krondor lives, has its own network of tunnels as well, some of which have been forgotten over time.
• The Ice Tunnels below the Castle in Septimus Heap.
• In Warrior Cats, the interconnected rabbit warrens underneath WindClan's forest territory, and the natural cave system underneath ThunderClan and WindClan's territories by the lake.
• Hogwarts Castle is comprised of these in the Wizarding World franchise, and there are so many secret passages hidden throughout the school that very few people know them all. Argus Filch is familiar with most of these tunnels, but several more are known only to the Marauders and whoever possesses the Marauder's Map (such as the Weasley Twins). The only parts of the school that don't show up on the Marauder's Map are the Chamber of Secrets due to it being considered a myth, and the Room of Requirement which is even more impossible to map than Hogwarts itself.
• The Dresden Files depicts a semi-fictional Chicago "Undertown".
• Isaac Asimov's The Caves of Steel features a very extensive road network underneath New York. It's restricted to police and emergency vehicles and is used by these to rapidly travel through the city. It's also considered fairly spooky even by the agoraphobic New Yorkers. An in-universe ghost story has a criminal fleeing from the police into the labyrinthine tunnels to escape capture. He does... and then finds himself completely lost and unable to find somebody, anybody, to help him out. The story goes that his ghost haunts the tunnels still trying to find safety.
• In Thud!, the dwarfs have created a tunnel network under Ankh-Morpork, partly so they can look for the McGuffin without anyone noticing, and partly because it wouldn't occur to them not to dig underground to where they want to go. By the end of the book, the network has been seized by the Patrician, who seems to have plans for it, possibly involving propelled carriages of some kind. (It's mentioned that the basic dwarfish mine sign, indicating a mine entrance, is a circle with a horizontal line through it.)
• Clockwork Century: Seattle has a network of sealed tunnels (adapted from the tunnels dug by the Boneshaker and the real-life Seattle Catacombs) because above-ground is infested by zombies and the Deadly Gas that creates them.
• The Tunnels series is built on these. Prominent examples include the tunnel network beneath Highfield, which serve as the ventilation for the Colony, an underground city connected by another tunnel network to the Eternal City, which was inhabited by the ancestors of the Styx before it was rendered uninhabitable by a plague. Deeper down, in the inner world, the ruins of the ancients are connected by another tunnel network, now inhabited by the "Bushmen."
• In Five Go To Smugglers' Top, the houses in the eponymous village are linked by old smugglers' tunnels.
• The Yiddish Policemen's Union. Inspired by the Warsaw Ghetto uprising, the Federal District of Sitka has a network of tunnels built as a defensive measure for street-fighting.
• Quite a number of BIONICLE books take place in such a location.
  • In The Darkness Below, the six Toa Metru investigate a leak in the underground levels of the Archives, an island-spanning museum and storage network housing numerous monsters, only to face the Krahka.
  • In Voyage of Fear, they traverse an underground river to reach The Outside World, discovering ancient secrets, like the long vanished archivist Mavrah and his beasts.
  • In Maze of Shadows, the Toa Metru return via one of the villain's many secret cave systems, facing yet more monsters like the Rahi Nui, the Karzahni and the Energized Protodermis Entity.
  • In Web of the Visorak, the Toa are on the run from an army of Giant Spiders and various other dangers in whatever derelict tunnel they can access, following a breach in the Archives that let all the ancient monsters loose.
  • In Inferno, the heroic Toa Inika and evil Piraka teams ascend to the underground chamber of the Mask of Life, taking separate routes and facing different challenges.
  • Invasion was a cancelled, lost book that was only partially finished, about the Toa Inika team descending down the Cord, an underwater rock tunnel. The place, housing dangers like a barbaric tribe of Zyglak and utilities like the Toa Terrain Crawler, was revisited later in Downfall.

Live Action TV

• On Hogan's Heroes they had a network of tunnels under the camp, and leading out of camp. To the point that it was a miracle the entire camp didn't turn into a sudden sinkhole. At one point while trying to move a snowman so the Gestapo won't find their tunnel entrance, Hogan paces out to a spot, looks at his men, and says "I think this is about the only spot in camp we don't have a tunnel underneath."
• 2000's Secret Agent Man (no, not the one with Patrick McGoohan) had an underground highway system that allowed the agents to drive great distances at high speed out of sight of anyone on the surface.
• The Get Smart Headquarters has this.
• Beauty and the Beast had an extensive underground network in association with the NY subway system, with a whole Secret Society down there.
• The Silence have a whole network spanning the entire surface of the Earth in Doctor Who, allowing them to control the human race without humanity knowing.
• The Torchwood Three team were based in one that included a disused secret underground railway connecting them (Cardiff) to London and Scotland.
• In Stargirl (2020), the Injustice Society operate out of a series of tunnels running underneath Blue Valley.
• The sewers, catacombs, and assorted tunnel networks in Los Angeles, Washington, and New York provided escape and ambush routes for every terrorist's 24-hour plan to destroy the USA.
• On The 100, the Reapers live in and travel through various abandoned tunnels left from before the apocalypse.
• Buffy the Vampire Slayer. Sunnydale has fourteen million square miles of sewers that the vampire/demon population use to move around in daylight. It's implied that the long-lived Mayor of Sunnydale designed the town so demons and vampires would have easy access to victims.
• In Stargate SG-1, the Tok'ra are fast tunnel builders. They move from planet to planet to escape detection and build tunnels underground to inhabit and hide on each new world.
• In Liv and Maddie, Parker Rooney built a network of "Parker Tunnels" that go around the neighborhood and even to the high school. Parker's tunnel obsession became a serious problem in the Season 3 finale, because the house was on the brink of collapse. Thanks to Joey's blunder in closing the tunnels, it collapses.
• The Covert on Navarro in The Mandalorian is in a vast series of underground tunnels that can be accessed through various buildings.

Podcasts

• In The Magnus Archives, Jane Prentiss uses one beneath the Magnus Institute to break into the Archives in MAG 38. The tunnels only become more important throughout the series, as in MAG 40 Martin finds Gertrude Robinson’s body in one of their chambers, a number of episodes in Season 2 deal with Jon’s explorations of the tunnels, it is revealed in MAG 79 that Jurgen Leitner has been living in the tunnels, and in Season 4, it is revealed that the Institute was deliberately built over them due to the tunnels housing the Panopticon of Millbank Prison, which is essential to the Eye’s ritual and houses the body of Jonah Magnus.

Tabletop Games

• Call of Cthulhu. Several adventures with ghouls and chthonians give them underground tunnel networks. The ghouls' tunnels often connect to graveyards.
• In Dungeons & Dragons, the Drow can move along underground passageways and emerge at various points on the surface.
• Traveller Classic Double Adventure Death Station. The drugged humans on a space station have cut through the deck and cut holes in the fuel tanks to create underdeck passages throughout the ship.
• Warhammer:
  • The Dwarfs have the Undgrim, or Underway, underground highways that connected their mountain holds in their empire's heyday that were big enough for steam-powered vehicles to help pull shipments of ores or other goods. But after the earthquakes that came with the Time of Troubles broke the back of their civilization, parts of this network have collapsed or been infested with Goblins, Skaven, or worse creatures. Dwarf miners still know their way around the mountains' tunnels, though, and when fielded as part of an army can use them to appear on the enemy's flank or rear.
  • The Skaven have a veritable Under-Empire that's even more expansive than the Dwarf Underway, spanning the Old World with tunnels leading as far as distant Araby and Cathay.
• In Warhammer 40,000, Necron tomb-worlds have catacombs you could lose a cathedral in, housing thousands upon thousands of dormant Necron warriors. Regularly an Adeptus Mechanicus expedition drops in on one, squees out at the Machine God's gift, and are promptly slaughtered when they start prodding around. The galaxy now has another Necron world to deal with.

Video Games

• 7554: Glorious Memories Revived, a Vietnam-set war FPS, features the Cu Chi Tunnels in one stage.
• Advanced Strategic Command allows to pool resources in buildings via either pipelines constructed by bulldozers or inconvenient direct contact of buildings. Not only this saves bothering with transport, but producing some units require more materials than the factory or dock can hold. Buried pipelines are more expensive than open ones, but preferrable: they doesn't hinder unit movement and to break one the enemy must bring a construction unit to it instead of simply bombing. Construction ships can build underwater pipelines to connect islands.
• Age of Mythology had a god power that created a tunnel that you could put in two different spots to transport units via the two tunnels.
• Tunnels under Rome serve as fast travel systems in Assassin's Creed: Brotherhood.
• In The Battle for Middle-earth 2, both the Dwarven faction and the Goblin faction had resource-mining structures that doubled as entrances to their respective Tunnel Networks.
• In Battlezone II: Combat Commander, the ISDF's Cerberus Base on Pluto has a network of tunnels large enough for their Hover Tanks to fit four abreast through. The tunnels are largely used for storage, with recessed cargo rooms and surface access into to warehouses. Similar tunnels are used in several of the deathmatch maps, where they can contain alternate weapons or health and ammo pickups.
• The GLA of Command & Conquer: Generals have, well (hey, guess what?), Tunnel Networks, which serve as both base defense and a way of instantly transporting ground units. One of their general abilities lets them have a tunnel exit burrow up anywhere on the map, potentially in the middle of an enemy base. And finally, all GLA buildings leave behind an underground bunker when destroyed, which if left alone will eventually rebuild the structure free of cost.
• Dawn of War's Imperial Guard buildings have this capacity, as well as certain catacombs in the Necron stronghold mission. While transport is instantaneous, there's a cooldown before a unit can be moved to another location regardless of the distance.
• Dragon Age: Origins has the Deep Roads, formerly a highway system for the dwarven kingdoms but now almost entirely held by the darkspawn.
• Since fortresses in Dwarf Fortress tend to be mainly underground anyway, they usually incorporate some degree of this. Dwarven and goblin civilisations also create large tunnels linking settlements created during worldgen, and beneath those there are three levels of naturally-formed cavern system that blur the line somewhat between this trope and Beneath the Earth.
  • In World mode, major cities have catacombs and sewers.
• In Fallout 3, Washington D.C. is such a ruin that the best way to get around is by going through its subway stations - which isn't to say that the going is easy, considering the raiders, mutants and ghouls that haunt the partially-collapsed passages. The Taft Tunnels appear to be purpose-built to be these, leading out from the Pentagon.
• The sewers in Fallout: New Vegas. The real Las Vegas also has a drain tunnel labyrinth inhabited by 1,000 people.
• In Foxhole, players can build tunnel networks and while the tunnels don't allow soldiers to warp across the battlefield, they do permit defensive structures to operate while unmanned.
• The sewers of New York in Freedom Fighters (2003) are utilized by the American Resistance to move about underneath the eyes of the occupying Soviets. In game, manhole covers mark points where you can quicksave and/or return to base if you find you don't have the right tools for the job at the moment. The subway tunnels are used similarly later on in the game.
• In Hitman 2, the Delgado cartel created tunnel network under Santa Fortuna to communicate with their mansion, their laboratories and their plantations.
• Inevitable in Minecraft, what with the mining and all. Tunnels are also a handy way to get around at night without having to deal with the zombies and other monsters that spawn on the surface, assuming you remembered to put torches down, of course.
• In Pokémon Diamond and Pearl, the Underground is a maze of tunnels that spans the entirety of the Sinnoh region some uncertain distance below sea level. It is supported solely by wooden scaffolding and otherwise has floors, ceilings, and walls made entirely of dirt. Unlike most other examples though, it isn't used for traveling from place to place (except within Sinnoh Underground), but rather, is used as a secluded place where people can set up remote homes and dig for valuable items.
• The Zerg in StarCraft have Nydus Canals.
• In Vietcong, Hawkins infiltrates some of these.
• Rising Storm 2: Vietnam has the various NVA and VC tunnel systems dotted around certain maps. While they can use all their weapons here, the US, South Vietnamese, and Australians are forced into using only their sidearms should they enter them.

Webcomics

• Annyseed features a large underground tunnel network that connects many of the residents of Skull Valley. In the webcomic we see Anny and Winston use one of the tunnels to get from Professor Tripadiculous' secret lab to Hamish the Swamp Dragon's cave.
• The eponymous institution in Tales Of Gnosis College has an extensive network of steam tunnels running underneath its campus, which it happens to share with an adjacent Catholic women's college. Eventually some enterprising students put them to the obvious use.
• Similarly, the steam tunnels at the eponymous institution Smithson, used by the campus superhero.

Web Original

• How to Hero recommends building a tunnel network on your superhero hideout for quick getaways. (They also suggest recruiting a team of prairie dogs to help you do it.)
• Rats SMP: Tubbo has constructed one in the Rattic, which he uses to get around all the other rats' bases; as he puts it, he "lives with everyone".

Western Animation

• On Archer, Tunt Manor is the center of one of these that spans much of Manhattan. Apparently one of Cheryl's deranged ancestors thought that the Underground Railroad was literal, rather than figurative, and wanted to catch escaped slaves to sell back to their owners. Just to prove how out of touch with reality he was, he had them built in 1890!
• In Pound Puppies (2010), the dogs base their operations in a central underground hub and use a series of tunnels beneath the shelter grounds to get themselves and puppies into and out of the pound.
• The bumptious Mayor on Pecola has a series of secret tunnels beneath the town which he uses to get himself out of tight spots (such as answering his constituents' probing questions).

Real Life

• Spider Holes in Vietnam.
• Catacombs.
• Along the U.S./Mexican border alien smugglers sometimes dig tunnels to allow their customers to pass under the border fence.
  • Other types of smugglers (e.g. for drugs) do this also; some of the tunnels are fairly impressive in their length and come out in basements quite some distance from the actual border. It's probably the lack of plausible deniability (you can't realistically argue you didn't know that tunnel in your basement led to Mexico) that keeps it from being more widespread.
• North Korea has dug incursion tunnels under the DMZ for use during an invasion of South Korea.
• Japan and Germany both had tunnel networks during WWII. Especially Japan.
• Palestinians have tunnels in Gaza and the West Bank that are used to, among other things, facilitate trade
• Iron Mountain in western Pennsylvania, where the U.S. government is prepared to hide in case of enemy attack.
• Prairie dogs dig vast networks of tunnels.
• Portland, Oregon, has a nifty system of tunnels, popularly known as the Shanghai tunnels, which according to possibly dubious 19th century historical record, were used to kidnap men (known as "shanghaiing") as free labor on the ships that sailed in and out of the city's port.
• More mundanely, many cities have tunnel networks with trains running though them.
• Fortresses of the Maginot Line were connected by tunnels, and presented a formidable defensive obstacle. Unfortunately, very few French military or political leaders gave much thought to what they were supposed to do if the Germans managed to get around them, and building the Line left very little money in the defense budget for modern aircraft or armored vehicles. When the Third Reich pulled a spectacular Dungeon Bypass after The Battle of Fort Eben-Emael, the end result was all but a Foregone Conclusion.
• The city of Tabor in Hussite War-era Bohemia had a full tunnel system dug beneath it (this was the early 15th century!). The system was designed so that the militia could rush through the tunnels to the heart of town if an enemy attacked, while the enemy was forced to negotiate a series of narrow streets so that no matter where they emerged, they'd walk into a massed barrage. The tunnels were full of food and beer to sustain the militia in case of siege as well.
• Walt Disney World has such a network to hide certain aspects of park operations from the customers (trash collection being primary).
  • To wit, Magic Kingdom's ground level is considered the second story. The first story is long corridors and filled land.
  • Disneyland's is much less extensive, but most of the restaurants in the New Orleans Square area share an underground central kitchen.
• Laval University in Quebec has all of its buildings linked by tunnels, so people can avoid being outdoors during the winter. Wright State University in Ohio has a similar system, with only two or three buildings left out of the loop. So does the Minneapolis campus of the University of Minnesota. (Many of these are steam and maintenance tunnels that officially are not for public access, but generations of students have learned about them.)
  • Large hospitals or museums, like academic institutions, tend to have a Tunnel Network for storage, physical plant, and secure transfer of material and personnel between buildings.
• Some Ice Age-era tunnels in South America, large enough for humans to walk upright within, are now believed to have been excavated by giant ground sloths. Generations of these immense mammals are thought to have occupied the largest, extending their burrows over the years or adding new side-branches, and leaving their distinctive claw-marks on the walls and ceilings.
• The Williamson Tunnels in Liverpool, a series of tunnels built beneath the city by an Eccentric Millionaire in the early 1800s. There are many theories about why they were built, ranging from make-work to employ jobless veterans after The Napoleonic Wars to bunkers to prepare for Judgement Day. The generally accepted one is that he did it as land reclamation to restore the ground level after quarrying for sandstone for his other building projects in the city. These tunnels were some of the primary inspiration for the Tunnels series.
• Metallurgical Combine Azovstal of Mariupol is one of the largest steel rolling companies in Ukraine, and it has a Soviet era underground tunnel network built during the Cold War in the advent of a NATO nuclear attack. It became the last pocket of organized resistance in the February-May 2022 siege by the Russian forces that invaded Ukraine, and many civilians of Mariupol took refuge in said tunnels.
• Washington, D.C. has a very un-secret tunnel network linking the U.S. Capitol to the Library of Congress and the various Congressional office buildings. This is useful to politicos and staffers going back and forth from their offices to the Capitol, especially when the weather is unpleasant, or they want to avoid flocks of tourists. There are also a few miniature subway systems for the use of said politicos and staffers.

---