See Aquatic Animal Tropes for creatures that reside underwater. Seaborne and Submersible Vehicles will usually be doing the exploring. Also see Subterranean Index and Index in the Sky.
Tropes:
- Artificial Gill: A device that allows a character to breathe underwater.
- Awesome Underwater World: The undersea realm depicted as awesome.
- Captain Fishman: Superheroes that specialize in deep sea crime-fighting.
- Cement Shoes: It's what you wear when you go sleep with the fishes.
- Creepy Old-Fashioned Diving Suit: Old model diving suits are scary.
- Dive! Dive! Dive!: Stock Phrase used on submarines or anything to do with something going down.
- Dive Under the Explosion: Diving into water to avoid an explosion.
- Eldritch Ocean Abyss: The deep sea is full of eerie and/or terrifying creatures.
- Fish People: Fish-like humanoids.
- Guns Firing Underwater: Guns can be practically drowned in water and still fire accurately, if not a little worse for wear.
- Oxygenated Underwater Bubbles: Inhale large bubbles to avoid drowning.
- Perilous Prehistoric Seas: Prehistoric seas are full of hardships for anyone who lives or travels there.
- Reed Snorkel: Using a reed to breathe underwater.
- Sea Monster: Giant aquatic creatures that live in large bodies of water.
- See Water: Underwater visibility is perfect in fiction.
- Shipshape Shipwreck: A lost ship perfectly preserved deep beneath the ocean.
- Sunken City: A city half-sunken, with buildings at unsafe and possibly nausea-inducing cants.
- Super Swimming Skills: A character can swim expertly, including underwater, without difficulty or exhaustion.
- Super Not-Drowning Skills: A character can hold his/her breath for long periods of time, or even indefinitely.
- Symbolic Serene Submersion: Floating motionless underwater as visual shorthand for a character's emotional state.
- Token Aquatic Race: A work has a variety of sapient species, but only one lives underwater.
- Under the Sea: Aquatic or underwater levels in video games.
- Underwater Base: An underwater Home Base.
- Underwater Boss Battle: A water-based boss fight in video games.
- Underwater City: An entire city of people living and "breathing" underwater.
- Underwater Fart Gag: If farting is funny, then it's even funnier when it's underwater, the reason being that farting underwater produces a bubble.
- Underwater Kiss: Kissing somebody while you're both underwater.
- Underwater Ruins: A city, ship, temple, or other place of majestic wonder submerged in water.
- Walk, Don't Swim: Walking underwater.
- Waltz on Water: Waltz music played in watery video game levels.
- Water Is Air: Life underwater is pretty much like regular life. Even physics agrees.
