->'' 'Tis a naughty night to swim in.''
-->-- '''Creator/WilliamShakespeare''', ''Theatre/KingLear''

Many people enjoy swimming from time to time, it's fun and a complete sport. Maybe you even like [[SurferDude taking the waves]]. Or maybe you just like the relaxing feeling of the sea. Or maybe you enjoy the water [[TwoPersonPoolParty in company]]. But [[GenreSavvy if you are in a fiction work]] you should only go for a swim in broad daylight, otherwise things tend to get a little messy...

No matter the place: the beach, a lake, a river, open sea or a swimming pool, if you go for a swim after dark you will die in the water or shortly after. It may be a SeaMonster out for dinner, it may be a SerialKiller stalking you, it may be an EldritchAbomination coming out of the sewers or maybe you manage to [[SuperDrowningSkills drown]] [[ArsonMurderAndJaywalking by yourself]] but no matter what, you are in for a gruesome death.

This can be TruthInTelevision to some degree, as swimmers are less likely to see aquatic predators such as [[EverythingsEvenWorseWithSharks sharks]] and [[NeverSmileAtACrocodile crocodiles]] at night, and such predators are often more active at night too. This is why many beaches close at night or at least warn people that night swimming is dangerous. In a similar vein, a human killer can take advantage of the [[HazardousWater water]], [[DarknessEqualsDeath darkness]] and often [[IneffectualLoner solitude]] of a night swimmer. Drownings also tend to take place at night, though this may be generally because it gives people plenty of time to have got drunk first.

Compare DarknessEqualsDeath where darkness means trouble, HazardousWater where the water indirectly contributes to your death and MurderWater where the water itself is trying to kill you.

'''As a DeathTrope, spoilers ahoy.'''

----
!!Examples of this trope:

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[[folder:Film]]
* Frequent in the ''Film/{{Jaws}}'' movies. The opening scene in the first movie is the most remarkable one.
* Happens to anyone who skinnydips at night in Crystal Lake in the ''Franchise/FridayThe13th'' movies.
* Parodied in ''[[Film/NineteenFortyOne 1941]]'' - girl goes swimming at night, gets caught on [[http://www.youtube.com/watch?v=-v93NKIFBBw a Japanese submarine.]] It's even the same girl who did the ''Jaws'' scene.
* Subverted in ''Film/CatPeople''. Although it doesn't end with a death, the suspension being built up pretty much forces you to expect it
* Averted in classical Finnish films ("Suomi-filmi"); skinny dips, nighttime or not, bring no greater harm than perhaps an unwanted admirer.
* ''Film/DeepBlueSea'' plays with this trope. It's subverted in the beginning as it seems everyone in the water is going to die, but they are saved by the protagonist. However later it's played straight and often, as most of the movie takes place during night.
* Averted in ''Film/{{Gattaca}}'', when Vincent and Anton go for a swim in a lake/ocean (it's not explicitly stated and there's minor problems with either option) at night during the film's climax as a CallBack to when they did the same towards the beginning. Vincent is stated as being at risk for a heart condition, and Anton was shown to be a better swimmer in the beginning of the film. Anton becomes afraid and gives up, while Vincent has already resolved that he will [[{{Determinator}} succeed or he will die]], and only stops to go back and [[ThickerThanWater help his brother]].
* Parodied in the opening scene of ''Film/{{Piranha}}'', in which a couple break into the research facility to take a dip in the pool and get eaten by the piranha inside.
* Despite the warnings, two lovers in ''Film/TheMonsterThatChallengedTheWorld'' go swimming in the moonlight, and they soon disappear beneath the surface.
[[/folder]]

[[folder:Literature]]
* In the BackStory to ''The Reincarnation of Peter Proud'', the title character goes for a swim at night. His wife rows out to him in a small boat and knocks him unconscious with a paddle, causing him to drown. The same thing happens in TheFilmOfTheBook.
** And, the reincarnated man recreates the swim as part of his plan to rid himself of the bad dreams of his former life. Unfortunately, the wife of the previous man follows him out as before. [[spoiler: He tries to stop her from killing with an oar as before, but this time she has a gun and he dies all over again. Bummer ending.]]
* One of the murder victims in ''[[Creator/AgathaChristie A Caribbean Mystery]]'' falls foul of the killer while swimming at night.
* In the book ''Siren'' the older sister drowns when she decides to go and dive off a cliff for fun in the middle of the night
[[/folder]]

[[folder:Live Action TV]]
* Too many ''{{Series/CSI}}'', ''Series/CSIMiami'' and ''Series/CSINewYork'' episodes to list. When this happens the usual is finding the body floating in the swimming pool.
* In ''{{Primeval}}'', a couple is swimming in a public pool at night, when a [[SeaMonster mosasaur]] joins them...
* In an episode of ''Series/{{Brimstone}}'', a young woman (who is one of the 113 escapees from Hell who makes for the show's McGuffin, and who went to Hell after she murdered the families of the men who raped her) goes swimming at night with her new boyfriend. When he gets a little too frisky and triggers her, her demonic powers kick in and she boils him alive in the water.
* Happens in ''Series/BuffyTheVampireSlayer'' in the episode where the swim team are turning into fish monsters.
* In ''{{Smallville}}'' Lana Lang once went for a night swim, at the high school pool if memory serves. Naturally she was attacked, and Clark saved her.
* A ''Series/{{Castle}}'' episode starts with the champion of a college swim team training in the pool after dark. Of course, he ends up being the {{body of the week}} not even two minutes into the episode.
[[/folder]]

[[folder:Music]]
* While the minor 1957 hit "[[http://www.youtube.com/watch?v=jbMJWa6FXTM Moonlight Swim]]" is actually just a standard [[SillyLoveSongs Silly Love Song]] of the era, once you know it's sung by the future [[Film/{{Psycho}} Norman Bates]] himself (Anthony Perkins) it's hard not to think of the trope anyway.
[[/folder]]

[[folder:Web Comics]]
* The plot of ''Webcomic/SchlockMercenary's'' Mahuitalotu arc [[http://www.schlockmercenary.com/2005-10-02 kicks off this way]].
[[/folder]]

[[folder:Western Animation]]
* A Halloween episode of ''WesternAnimation/TheSimpsons'' has Lenny recreating the opening scene from ''Film/{{Jaws}}'', except with dolphins in place of a shark.
-->'''Lenny:''' Alcohol and night-swimming! It's a winning combination! (dolphins appear) [[OhCrap Oh no]], sharks! The assassins of the sea!...Wait, you're dolphins, the clowns of the sea.
-->[[WhosLaughingNow *The dolphins proceeded to beat and bite him to death*]].
[[/folder]]