Water can be one of the most dangerous things in a horror film. You're not likely to drown in it, but there are other reasons to avoid it like the plague:
- Teleportation Hazard: If you fall into the water, in the next shot, you are likely to be a dozen yards away from dry land, easy prey if the killer is in the water.
- Stalling Hazard: If you fall in, but are just a couple feet from safety, the water will not let you move forward, no matter how frantically you splash around.
- Obscuring Hazard: If the killer is in the water, either the water will be opaque until the killer appears, or we see the killer rising up, but the victim will be forced by the water to look in the opposite direction.
If this trope is in effect and the killer is not human, then the monster is often a hideous water-dwelling creature.
Compare Drowning Pit (water as Death Trap), Super Drowning Skills (where water acts like a Bottomless Pit), Grimy Water (where going into the water hurts you), Murder Water (where the water itself is actively trying to kill you).
Examples of Teleportation Hazard:
Examples of Stalling Hazard:
- Seen this as early as Jaws 2, where a character is unable to get herself from safety as the shark approaches her.
- In 28 Weeks Later, the penultimate survivor in the opening doesn't make it because he falls off the motorboat; the infected are still about 30 seconds away, but he still can't reach to get on the boat. Even the editing looks shot to hide how close he was to safety.
- In Blue Demon, a Jaws ripoff about mutant sharks from a government experiment, there is this scene where a girl and her father are fishing off a pier, and one of the loose sharks jumps out of the water and knocks the father into the lake (actually, the shark leaps up, nobody reacts, and then the actor makes an obvious show of falling in). He takes about thirty seconds to get back on the pier, but it's obvious the actor is just splashing around, and not actually trying to swim back to safety until he's supposed to do so.
- The Devil at 4 O'Clock tries to justify this with a reference to the water as "quicksand," but examination of it reveals that it's liquid enough that swimming shouldn't be a problem. The swimmers are quite obviously swimming in place—expected for the drowning fellow, who's blindly panicking, but not so much for the fellow trying to rescue him.
- A murder sequence in Psycho ripoff Dementia 13 has the victim swimming to the edge of a lake, only to encounter the ax-wielding killer standing on the shore. Does she swim back the way she came? No. She just thrashes around and screams while he chops her up.
- In the first Kingdom Keepers book, Finn and Philiby have to navigate Splash Mountain without a log. Oddly, neither has a plan for navigating the big drop until just before they drop it.
- Justified in Metal Gear Solid 2: Sons of Liberty with the sediment pool; the oxygen level is so high that buoyancy is practically nonexistent. Of course, Vamp goes on to swim perfectly fine through it even after explaining that you will immediately sink and drown if you fall in, but after Vamp's last scene had him running over normal water and then up a ninety-degree incline, one kind of expects him to not play by the rules.
- Falling into turbulent water in the Tomb Raider series is instant death. One level also has a river with a current that prevents you from swimming and will carry you into a pool of man-eating pirahnas.
Examples of Obscuring Hazard:
- In Hollow Man, Sebastian Caine (the invisible Villain Protagonist) drowns a man in his own swimming pool. The victim's wife can see the vic kicking around in the pool but not Caine, and doesn't realize anything's amiss until it's too late. (We, however, see a very cool ghostly outline of the submerged Caine.)
- Used throughout the story in River of Teeth, but especially when the gang is traversing the marshlands south of the Harriet. Since hippos dwell in the water and can navigate the marshlands unseen, and the feral hippos in the area are especially vicious, traversing the bayou during the day is dangerous and nobody wants to go near the water at night at all. Despite that caution, nobody sees the feral hippo before it attacks and kills Neville.
- A CSI episode dealt with a killer who killed his victim by wearing scuba gear and waiting in the victim's (somewhat cloudy) pool. To aid him, he did wear a body suit that looked somewhat like the pool's bottom.
- In Fantasy Flight's Descent boardgame the players battle their way through dungeons filled with Demons, Beast Men, Giant Spiders, and Chaos Beasts. Water is an uncrossable barrier (like a chasm). When players asked why there was no swim skill, the designer (in the FAQ) responded that there is but it's useless. All water underground is infested with Blood Squid, capable of killing any living thing instantly. This is also why there are no aquatic monsters.....
- In most of the Ratchet & Clank games, pools of water almost invariably contain lombax-eating giant fish. They may or may not be visible without falling in and dying.
- You can swim in the creature stage of Spore, but going too deep means you get eaten.
- In the sewer area of Batman: Arkham Asylum, Batman must move slowly and quietly as Killer Croc is lurking under the surface. He'll still pop up time to time, but making too much noise will let him pinpoint your position, allowing a point-blank attack.
- In a Thieves' guild mission of The Elder Scrolls IV: Oblivion, far from the water's surface is a giant jawfish. The water is opaque in that direction because the view is blocked by the small opening into the larger reservoir it inhabits. About the time you see it is when it begins swimming directly at you.
- The Kaernk from Amnesia: The Dark Descent lurks in the water, but instead of the water being opaque, the Kaernk is invisible and can only be seen when its moving with its footsteps visible.
- In the Fallow Mire level from Dragon Age: Inquisition, stepping into the water will prompt groups of walking corpses to rise up and attack you.
- In Anaconda, the Amazon water is downright lethal; besides a giant man-eating reptile making it hazardous to even move in, the characters also mention various other nasties that could attack a swimmer like parasitic fish and poisonous wasps.
Gary: There's something down there.
Sarone: I know.
Gary: No, I really mean it.
Sarone: I really mean it too.
- In Ghost Shark, any amount of water will allow the titular ghost shark to pop up and eat you. Even a Slip 'n Slide.
- In The Bay, the town's water supply is contaminated by a mishmash of pollutants from chicken farm runoff and microscopic eggs and larvae of giant tongue-eating sea lice that devour humans' flesh from the inside.
- Kellwood lake in Charby the Vampirate is full of man eating monsters rather like the surrounding forest.