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Artificial Gill

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"Want to breathe underwater? How about taking a space walk? You can even survive in poisonous atmospheres with the O2 Mask from Gadgetron! This mask auto-equips whenever it senses that you need extra oxygen! Or if you prefer, you can equip it any time and wear it for its stylish looks. "
—Description for the O2 Mask, Ratchet & Clank (2002)

In fiction, characters may for whatever reason need to stay underwater for an extended period of time. In Real Life, this can be accomplished with SCUBA gear for short periods (about 1 hour) or rebreathers for much longer periods — however, these real world devices are bulky, require a lot of training (especially rebreathers), and are priced well beyond many people's means.

Obviously, these concerns would bog down most fantasy or science fiction narratives. The solution? The Artificial Gill: A device that enables a character to swim underwater without worrying about the Oxygen Meter, unless the device runs on air tanks. These are used to find and explore Underwater Ruins and the Underwater City.

See also Super Not-Drowning Skills. The inverse, which allows an aquatic character to handle non-aquatic environments, is a Mobile Fishbowl.


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    Anime and Manga 
  • 008 from Cyborg 009 has this as one of his cybernetic enhancements, as well as other modifications that allow him to survive deep sea pressures, even having most of his skin replaced with metal scales as a Midseason Upgrade after being blown up. The other cyborgs have built-in oxygen tanks that let them hold their breath longer than a normal person, but 008 is the only one who can actually breathe water.
  • Professor Fumble in Marine Boy invented "Oxy-Gum," which lets Marine Boy get all the oxygen he needs for hours from simply chewing the gum.

    Comic Books 
  • Batman carries a rebreather in his utility belt.
  • Robin (1993): The limitations of a rebreather are displayed when Tim gives his to a gangster he'd been chasing that ended up pinned underwater by falling debris. Tim struggles to try and pull the large structural beam off of him while he slowly drowns.

    Fan Works 
  • The The Legend of Zelda fic Zelda and the Manacle of Cahla, where the traditional dynamics are reversed and Zelda is the hero, has the Pearl Mask, which allows its wearer to breath water instead of air. Zelda retrieves it from the Blue Swamp to settle a dispute between Zora factions, but Prince Tyrus lets her take it on her journey.
  • Vow of Nudity: Haara uses a potion of water breathing in one story to investigate an ocean shipwreck.

    Film — Animation 
  • Big Hero 6: Downplayed. One exhibit briefly shown at the SFTT Showcase is a man underwater breathing through such a device.

    Film — Live Action 
  • The Abyss has a gooey gel that is hyperoxygenated for super-deep-sea diving. This is a real thing. The scene with the rat was a real rat really being held under the surface of the liquid and freaking out because it had no idea what was going on. Animal welfare groups were annoyed about it because they thought it was being put in unnecessary distress.
  • James Bond has made use of this device.
    • He uses a mini-breather in Thunderball when escaping the shark pool and later when fighting mooks underwater. After the movie came out, a naval engineer spoke to the producers, inquiring how they managed to make the mini-breather, since he was trying to develop one himself. He was devastated by their answer: Sean Connery was actually holding his breath.
    • In Die Another Day, he uses a rebreather when scuba-diving his way into the villain's lair.
  • At the end of Sherlock Holmes: A Game of Shadows, Watson receives Mycroft's oxygen inhaler in a parcel sent by Holmes, who stole the inhaler from his brother and used it to survive when he pulled Moriarty down the Reichenbach falls with him.
  • Star Wars has Rebreathers, used for breathing in hazardous environments, including underwater. A notable example is from The Phantom Menace, where Qui-Gon and Obi-Wan use them to swim down to the Gungan city.

  • Animorphs: One book has the Yeerks attempt to modify their Hork-Bajir (humanoids with dinosaur-like traits) hosts with gills for underwater environments. Keyword being attempt, they botched it up so badly that the Hork-Bajir essentially drowned on dry land.
  • In Dark Life, there is liquid oxygen that allows people to live underwater.
  • Doc Savage not only had diving suits more advanced than anything available in Real Life at the time, but also 'oxygen tablets' that supplied oxygen directly to the blood and allowed the users to survive underwater for about two hours.
  • Goblin Slayer: The Breath spell is normally just used to allow people to breathe underwater. However, Goblin Slayer demonstrates that the spell accounts for all forms of water including snow and ice, which allows him to survive being buried by an avalanche. He also utilizes the Required Secondary Powers of the spell that protect the user from changes in temperature from water immersion to help his companions stay warm in a snowstorm.
  • Harry Potter and the Goblet of Fire introduces gillyweed, a plant that when consumed causes the eater to temporarily grow gills. Another option is the Bubble-Head Charm, which surrounds the subject's head in a bubble of air to let them breathe normally (at least until the air runs out — but hey, A Wizard Did It).
  • Rifters Trilogy: The Rifters do not breathe air when they leave the habitat. Instead, oxygen is electrolyzed directly from the seawater by an electrolysis assembly in the left side of their thorax, which is then introduced directly into their pulmonary vein.
  • Star Wars Expanded Universe novels:
    • On Admiral Ackbar's planet Mon Calamari (seen in Dark Apprentice), they have flexible, jelly-like breathers called "organic gills" or "oxygen symbiotes" that most species (Sullustans are allergic to the organic gills) can slap over their nose and mouth, where it filters the water into oxygen.
    • The Yuuzhan Vong in the New Jedi Order series have a similar creature called a gnullith that covers the nose and mouth, and extends down the windpipe to interface with the lungs directly. It's incredibly useful, even because it doesn't need recharging of any kind, and unlike their other biots, gnulliths cause no pain or discomfort.
  • Poul Anderson's fantasy novel Three Hearts and Three Lions sees the hero, Holger Carlsen, abducted by a nixie (a freshwater mermaid - think Rheinmaidens in Wagner opera). She confers on him the gift of being able to live and breathe underwater, but capriciously cancels his artificial gill when he declines her kind offer to live with her underwater forever.

    Live-Action TV 
  • Babylon 5: A number of species need to use breathers when going into the "alien sector" of the Babylon 5 space station, and several others need to use breathers to travel in the nitrogen-oxygen atmosphere throughout the rest of the station. Also, G'Kar has gills surgically added that allow him to breathe in alien atmospheres without a device. Lyta Alexander gets her own set of gills after being Touched by Vorlons.

    Tabletop Games 
  • Early editions of Dungeons & Dragons
    • A number of magical items had this ability, such as the Helm of Underwater Action, the Cloak of the Manta Ray, Potions of Water Breathing, the Necklace of Adaptation and the Ring of Water Adaptation.
    • Spells: the Airy Water and Water Breathing spells.
    • "Natural" magic items: module EX1 Dungeonland had seaweed that allowed breathing underwater. There were similar items in other adventures.
  • The artificial gill and the gill suit from GURPS: Ultra-Tech allow people to spend hours or even days underwater. In High-Tech SCUBA and rebreather gear is available. Even as far back in time as Low-Tech it's possible to get waterproofed animal skins that give a few extra breaths if used correctly.
  • While they don't come up very often in Mage: The Ascension, the Void Engineers have them for their underwater corps (they explore everything, not just space and other dimensions). They're starting to get more notice as of the most recent edition, when many Technocrats have had to relocate to the Void Engineers' Underwater Base locations due to the Avatar Storm.
  • Shadowrun has a few pieces of equipment and cyberware that can provide this, but conventional air tanks are much cheaper. Also, large bodies of water in the Shadowrun universe are often quite polluted so few people want to go voluntarily swimming in them.

    Theme Parks 

  • BIONICLE: the Kaukau and Kaukau Nuva, a.k.a. the Masks of Water Breathing. These filter oxygen out of the water and allow the wearer to breathe.
    • Later on, the Toa Inika are transformed into the Toa Mahri, who have "gills" that look like breathing tubes. Lesovikk and Hydraxon also have the same sort of gills, though in Lesovikk's case it was due to the Pit mutagen.

    Video Games 
  • The Aqualung item in Alter A.I.L.A. Genesis. You actually can't go underwater at all until you get it. Also lampshaded when it's obtained, as the character that normally explains these kinds of things says she has no idea how it works.
  • A recurring item in the Atelier Series of games is the Air Drop, which is this trope in candy form! Made with alchemy, they take the form of either a hard mint or something similar to Mentos, which releases breathable oxygen in one's mouth, letting them breathe underwater.
  • Borderlands: The Pre-Sequel!: The Oz kit in allows the characters to breathe in space.
  • Breath of Fire:
    • Breath of Fire I required you to find a gill key item to let any character other than Gobi (a fishman) travel underwater.
    • Breath of Fire II featured such an item as well.
  • In Cave Story, Curly Brace has an air tank... which makes the player character's susceptibility to drowning all the more frustrating. She eventually gives you the air tank.
  • Commander Keen 4 has a set of scuba gear, but it has an unlimited air supply.
  • Deus Ex has rebreathers that allow you to breathe underwater for a limited time. The prequel features an Implanted Rebreather that does the same for poisonous gases but not water (or at least we don't see it do so, because you never go underwater).
  • On the Online Games by Artix Entertainment, it was finally explained why you can breathe underwater in all 5 games: In DragonFable, you sink a ship full of water breathing potions that contaminates and enchants the ocean so that you can breathe underwater.
  • The SCUBA Gear is a signature item in the Build engine games. Duke Nukem 3D, Redneck Rampage, and Blood (1997) all have an item that lets the player spend several minutes underwater, as opposed to maybe 30 seconds without it.
  • In The Elder Scrolls series, starting with Daggerfall, the series offers spells, potions, and enchanted items with the Water Breathing effect. These allow you to remain underwater without needing to surface for the effect's duration (or in the case of constant effect enchanted items, for as long as you have the item equipped).
  • EXTRAPOWER: Attack of Darkforce: When the cruise ship the heroes were using to traverse the Pacific sinks, they are taken by Captain Nemon to the kingdom of Deep Haven. Naturally, the surface-dwellers cannot breathe underwater, so they are given an ointment that permits them free movement in the atmospheric pressures of the ocean floor and to comfortably breathe. This becomes a a Chekhov's Gun for the end game, as Dark Force cannot be confronted directly thanks to his gravity-control powers making it impossible to move. The team realizes they could use this same ointment to move freely in the gravitational field as easily as they can under the ocean pressure.
  • Fallout 4
    • The Aquaboy/Aquagirl perk allows the Sole Survivor to indefinitely remain underwater. Being the sole game of the franchise where you will run into a lot of water this perk is invaluable, especially in the early game where you can't find any Rad-X or Rad-Way to deal with the constant radiation in the water.
    • The Power Armor increases the length of time you can stay underwater, but you can no longer swim in it. This is bad in the Dunwich Borers quarry which has a very deep pit of water at the end of the dungeon as there is no way of getting your power armor if you jump in.
    • The Far Harbor DLC adds the BioShock-style Rescue Dive Suit.
  • Fallout: New Vegas gives you a rebreather if you help the Boomers, but other than a related mission and two caves there is absolutely nothing to see in the depths of Lake Mead. However there are certain areas of Vaults that happen to be submerged.
    • It also comes in useful in searching a few submerged areas in the Honest Hearts and Old World Blues DLCs.
  • Oxyale in Final Fantasy
  • In Guild Wars 2 every character has one standard, because the dev team did not want to limit the underwater areas' size to how long you could hold your breath.
  • Partway through Horizon Forbidden West Aloy must craft the Diving Mask in order to explore a flooded ruin in Las Vegas. From then on she's able to explore any underwater section in the Forbidden West.
  • In the King's Quest II fan remake, a mermaid gives King Graham a kiss that somehow lets him breathe underwater.
  • The Legend of Zelda series has many items that serve this function:
    • Zora's Flippers appear in many of the 2D games, and sometimes allow Link to breathe underwater. Other times, they only allow him to swim in deep water and still require him to come up for air periodically.
    • The Legend of Zelda: Ocarina of Time has the Zora Tunic that lets Link breathe underwater.
    • The Legend of Zelda: Oracle of Ages has the Mermaid suit. Both Ages and Seasons also have the Zora Ring, which allows you to stay submerged in shallow water for as long as you want.
    • Twilight Princess has the Zora Armor. When Link is underwater, a small mask covers his nose and mouth, letting him breathe underwater.
  • In Mana Khemia 2: Fall of Alchemy, the access to Deep Sea Ruins is opened after you synthesize Air Drop. Said item also returns in Atelier Rorona.
  • Variation; it's a spell in MARDEK that can only be cast by a specific party member. A straighter example would be the Oxyale, a consumable potion that bestows the same effect.
  • In the Metroid games, Samus Aran's Powered Armor has a self-contained life-support system that can function as this - no Gravity Suit required. It even works in space!
  • Minecraft: The Turtle Shell is a helmet made from turtle scutes that gives the user 10 extra seconds of air while diving underwater.
  • The leaves of the Maurera Tree in Phantasy Star II can be refined into special chewing gum to provide oxygen while travelling underwater; this is used to reach Climatrol.
  • The O2 mask in Ratchet & Clank allows Ratchet to survive in toxic atmospheres, underwater, and even space with unlimited air supply. In Going Commando and Up Your Arsenal the Megacorp Helmet serves this purpose instead, and from Tools of Destruction onwards the helmets were replaced with a mouth-only variant.
  • Sonic 3 & Knuckles featured the bubble shield, which bestowed Super Not-Drowning Skills.
    • Knuckles picks up the Air Necklace as one of his power-ups in Sonic Adventure 2, allowing him to stay under indefinitely.
  • The Survival System backpack in Starbound allows one to breathe indefinitely underwater, as well as in space.
  • Mario gets one for the Bottle levels in Super Mario Sunshine. It extends the time he can breathe underwater without grabbing coins.
  • Terraria has an accessory that allows for underwater breathing.
  • Unreal:
    • Unreal
      • The core campaign has SCUBA gears available whenever the player must proceed a long way underwater. They have a limited air supply that runs out pretty quickly, and for some reason you can't just take a whiff from it and hold your breath to make it last longer — if you deactivate it manually, you'll immediately start drowning.
      • The Return to Na Pali Expansion Pack features the Marine SCUBA Gear as starter equipment that Prisoner 849 is sent down with. It's a much-improved SCUBA Gear that holds more air and recharges when out of the water.
    • The SCUBA Gear reappears in the Oceanfloor assault map in Unreal Tournament, and nowhere else.
  • World of Warcraft makes extensive use of this trope:
    • Class-specific spells; druid Aquatic Form, warlock Unending Breath, and shaman Water Breathing.
    • Crafting provide water breathing potions and the Deepdive Helmet created by engineering.
    • A weapon from Gnomeregan also functions as an Artificial Gill.
    • As a whole, Blizzard learned during Wrath of the Lich King that underwater quests were a pain in the ass and most such quests now provide a renewable Artificial Gill buff. Cataclysm adds the game's first underwater zone, Vashj'ir, and the first couple of quests are to gain a permanent, zone-only Artificial Gill that also provides substantially faster swim speed, without which Vashj'ir would be all but unplayable.
  • Wizard101 has underwater breathing potions early in the game to allow access to a street that is completely underwater. However, due to the game mechanics, players can teleport to this area without adverse effects.
  • In Ys VI: The Ark of Napishtim and Ys SEVEN, Grattheos' Talisman allows Adol and his party to breathe underwater.. In Ys VIII: Lacrimosa of Dana, the Hermit's Scale serves the same purpose.

    Western Animation 
  • The Deep (2015) has the Nektons using handheld rebreathers when they don't have their full face-covering oxygen masks at hand.
  • Flash Gordon (1979) has an episode featuring a literal Artificial Gill: it's a metal collar with gills that also prevents the wearer from breathing outside of water.
  • Futurama: The crew is given rebreathers when they find the lost city of Atlanta. And suppositories to help them with the pressure.
  • Kim Possible uses a rebreather provided by Wade in an episode where Drakken seals her in a filled-with-water bottomless pit.
  • Miraculous Ladybug: Ladybug and Chat Noir's weapons can function as these when they have to swim underwater. They also let other people use them while they themselves are transformed with a potion that gives them Super Not-Drowning Skills.
  • Samurai Jack: Jack is given a device to help him breathe underwater while swimming to the submerged Humongous Mecha.
  • In The Simpsons Bart once used Milhouse's inhaler as a breathing device.
  • The Gills of Hamachi from Xiaolin Showdown, although it achieves this by turning the user into a literal fish person.
  • Young Justice (2010):
    • Robin I/Nightwing carries these as part of his standard equipment. After three missions in a row nearly lead Artemis to drowning, she starts to carry them, too.
    • At some point between seasons 1 and 2, they were regularly stocked on board the bio-ship. Lagoon Boy seriously messes up when he forgets to replenish them for a mission.

    Real Life 
  • True artificial gills are highly impractical because humans require far more oxygen to sustain life than typical sea creatures. In order to get enough oxygen to sustain a human, several gallons of water must be processed per minute, and a device capable of doing this would end up being massive. Carrying such a heavy device would increase our oxygen demands further, compounding the problem. It's simply much more efficient to use compressed air for our underwater needs.
  • Modern underwater gear generally falls into two categories, tanks of compressed air, and rebreathers. The former exhales directly into the water (leading to the characteristic bubbles), while the latter simply filters out the CO2 and adds oxygen so the nitrogen can be re-used. It still has some gas, so it's only a partial example. Older designs simply pumped air down from the surface using a tube.
  • The Hydroid Aquabreather (currently under development with no concrete release date) is intended to come closer to this trope than most real-life diving equipment. The entire system is contained within a helmet, where potassium superoxide absorbs CO2 from exhaled air and releases oxygen. The main problem there is that potassium superoxide reacts explosively with water — if the system were to spring a leak, things could get ugly (which is why nearly all rebreathers in use are based on less dangerous chemicals which only absorb CO2, supplying oxygen from conventional tanks).
  • Mosquito larvae have a biological snorkel that they use to breathe from just below the surface of the water. All aquatic snails also have snorkels.
  • Some species of aquatic turtles have sections of skin near their rumps that have high amounts of blood vessels in them. They're able to passively absorb some oxygen directly from the water through these sections of skin, effectively breathing through their butts. It doesn't completely eliminate the need to breathe, but it does allow them to stay underwater for hours without surfacing as long as they're not moving around much.