->''"Don't drink the ocean, K'nuckles! Seawater makes you crazy! Look at me! I've been drinking it for hours!!! [[LaughingMad NYEHAHAHAHAHAHAHA!]]"''
-->--'''Flapjack''', ''TheMarvelousMisadventuresOfFlapjack''

Related to SpaceMadness.

Being away at sea for a long time seems to take its toll on your mind. Maybe it's the unchanging landscape, maybe it's being away from your loved ones. Either way, in period pieces and even sometimes in modern ones, you can expect any characters away on sea for extended periods of time to go crazy.

Historically a TruthInTelevision. In addition, there's a lot of validity to the "don't drink seawater" idea, since salt water has the nasty effect of making you even ''more'' dehydrated, which can lead to delirium. And, y'know, death.

Compare CabinFever.

[[WesternAnimation/{{Futurama}} Note that this is no excuse for ocean rudeness]].
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!!Examples:

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[[folder:Anime & Manga]]
* Hikari and Ken from ''Anime/DigimonAdventure02'' go mad (or at least have very bad {{FreakOut}}s) whenever they return to the Dark Ocean
** Though it's less from the usual reasons, and more because they basically stumbled into a CosmicHorrorStory.
* In the {{Omake}} episode of ''[[Anime/TsukuyomiMoonPhase Moon Phase]]'', Seiji Mido has gone completely mad from being trapped out at sea for several weeks. Though he could be considered the OnlySaneMan, as everyone else is completely blase at their house being intact and floating in the middle of the ocean (the giant cork just has to be left alone).
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[[folder:Film]]

* Results in a [[DisneyAcidSequence particularly delirious]] musical number in ''MuppetTreasureIsland''.
-->We've got Cabin Fever!\\
We've lost what sense we had!\\
We've got Cabin Fever!\\
We're all going ''mad!''
* Arguably, Tom Hanks in ''CastAway''. He wasn't strictly "at sea", per se, but he fits the rest of the trope.
** On the other hand, what sent him round the twist was probably spending several years with only a (Goddamn) volleyball [[CompanionCube called Wilson]] for company rather than being surrounded by ocean.
*** On the yet another hand, Wilson may actually have kept him from going frothing mad by virtue of being "company" to talk to.
* Tom Hanks again in ''[[JoeVersusTheVolcano Joe vs the Volcano]]'', after days of solitude, dehydration, and exhausting the entertainment potential in his luggage.
* An anti-OceanMadness might be Jack's locker-induced madness at the beginning of ''Film/PiratesOfTheCaribbean: At World's End'' -- Hell for a pirate, seemingly, is a barren endless salt flat far from any sea.
** Well, it's definitely Hell for ''Jack'', who has been known to mention that he considers the sea - and having a ship of his own - is one of the few things he actually considers to be worth living for. It's entirely possible that the Locker would appear differently to other people who were trapped in it (as opposed to the rest of the cast, who essentially come into Jack's head).
* ''Film/MasterAndCommander: [[ColonCancer The Far Side of the World]]'' has a significant subplot concerning an officer who comes to believe he is a curse on the ship. [[spoiler: [[DrivenToSuicide He kills himself.]]]]
** [[spoiler: His treatment at the hands of the rest of the crew - most of whom shun him - does not help matters. He might not have gone through with it if he'd had any reason to believe that *anyone* on that ship truly believed that he wasn't a Jonah.]]
*** [[spoiler: Jonah, nothing.]] Put a disturbed, neurotic young man ''as an officer'' on a ship where everyone treats him like a pariah [[spoiler: and he just got a man flogged for disrespect]] and you have a recipe for serious depression. [[spoiler: His suicide would be understandable even without believing he was personally cursed.]]
* Coffey in ''TheAbyss'' quickly descends into ocean madness - High Pressure Nervous Syndrome, to be precise.
* In ''Disney/TheLittleMermaid'' when Prince Eric wakes up on the beach and starts talking about being rescued by a girl, Grimsby replies, "I think you've swallowed a bit too much seawater."
* The end of ''The Road to Morocco'' has a ship exploding. Bob Hope, adrift on a bit of wreckage, goes into a hyper-dramatic fit of madness, until cohort Bing Crosby points out they're practically at the docks of New York - Bob chides him for ruining his chance for an Oscar.
* ''Film/CabinBoy'' has an extended ocean madness scene that involves a tobacco spitting, foul mouthed cupcake.

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[[folder:Literature]]

* ''Literature/TheRimeOfTheAncientMariner'' is essentially about a crazy old man accosting a random guy in the street and making him listen to an extremely gruesome experience of Ocean Madness. Hopefully. Because if he was actually sane when he saw all that stuff out there...
*** The fact that [[ReallySevenHundredYearsOld the Mariner might be close to a thousand years old]] would seem to corroborate his story, unless every single detail, including when it happened, is a hallucination.
* In ChinaMieville's ''Literature/TheScar'', Hedrigall decides to leave Armada, the floating city, and spends some time alone at sea. After he is found he has been driven mad by [[DoomedHometown seeing his entire city destroyed]].
* ''Literature/{{Cryptonomicon}}'' has Goto somehow managing to swim all the way from open sea to New Guinea. As an Okinawan who grew up in the sea, he knows damn better than swallowing the sea water. Problem is, he's swimming with a Tokyo city mouse, who doesn't knows any better... and after swallowing the sea water for a while, he slowly starts losing it, until he collapses in the shore while laughing sardonically...
* Captain Wolf Larson, in Jack London's novel ''Literature/TheSeaWolf'', starts off as a sadistic NietzscheWannabe, but degenerates into a full-blown psychopath with a [[DeathSeeker death wish]].
* From ''{{Nation}}'': "''Calenture''...meant a special kind of madness...sailors got [it] when they'd been becalmed at sea for too long. They'd look over the side and see, instead of the ocean, cool green fields. They'd leap down into them and drown." Although, since it's First Mate Cox doing the explaining there, it's possible that he [[KickTheDog pushed them in himself]].
** Creator/TerryPratchett had already mentioned the phenomenon in ''Discworld/GoingPostal'', where he uses it as an analogy for what happens to clacks operators after a while.
* Likely happened to Pi in ''Literature/LifeOfPi'', becoming most of the conflict in the story (the rest being stuck on a boat with [[PantheraAwesome a tiger]].)
* Inverted in Creator/JohnMasefield's "Sea-Fever":
--> I must go down to the seas again, to the lonely sea and the sky,
--> And all I ask is a tall ship and a star to steer her by,
--> And the wheel's kick and the wind's song and the white sail's shaking,
--> And a grey mist on the sea's face and a grey dawn breaking.
* Lampshaded by Wolf Boy in ''Literature/SeptimusHeap'', who thinks that he'd be driven to madness by the vastness of the sea.

[[/folder]]

[[folder: Live Action TV ]]

* In the TV-movie of ''Noah's Ark'', after the rain ends, the ark drifts for weeks across a sun-drenched and scientifically impossibly ''dead calm'' sea, and Noah and his sons and daughters-in-law all gradually go around the bend. However, Noah's ''wife'', being the Mommeee, is supposed to be an infinite source of self-sacrificing nurturance, so when ''she'' starts to crack, all the other characters stare at her in shocked amazement and suddenly go sane again.
* On ''{{Lost}}'' the crew of the freighter is slowly going mad while anchored near the Island. However, the main cause is the time-twisting effect of the Island rather than just being at sea.
* One surreal bit-scene on ''Series/TheYoungOnes'' featured a couple of rag-clad men lying on a ramshackle wooden raft. As they discussed [[ThisIsReality whether or not they were hallucinating]], their raft alternately appeared floating at sea, then lying on the floor in a cellar, then lying in the cellar of a house ''that was floating at sea''.
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[[folder: Tabletop Games ]]

* The background for the villain Cannibal from the Dark {{Champions}} sourcebook ''Murder's Row'' involves him going mad while stranded on the ocean in a lifeboat and discovering he has [[IAmAHumanitarian taste for human flesh...]]

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[[folder: Video Games]]

* VideoGame/SunlessSea, the VideoGame/FallenLondon spinoff. "Go Insane, Eat Your Crew" is one of its main slogans, and indeed one of the major challenges of the game is keeping the terror of the Unterzee from driving your crew violently insane.

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[[folder: Western Animation ]]

* In ''WesternAnimation/TheSimpsons'', Homer, Bart, Ned and Todd start to succumb to this after they get stranded out at sea in a raft.
* The TropeNamer is ''WesternAnimation/{{Futurama}}'', despite this instance actually being a CassandraTruth. When the crew gets stranded underwater, Fry sees a mermaid, resulting in everyone brushing it off as ocean madness. However, Fry really ''did'' see a mermaid, and no one actually goes mad.
-->'''Fry''': "Everytime something good happens to me you say I have some kind of madness. Or I'm drunk. Or I ate too much candy."
-->'''Leela''':"It's ocean madness all right, the sailors call it "Aqua Dementia". The deep down crazies, the wet willies, the screaming moist..."
* ''XavierRenegadeAngel'' has a variant. (''SAAAAAAAND MADNESS!'')
* Referenced in ''RoadToElDorado'' after Miguel, Tulio, and their horse Al Tivo have been floating for God-knows how long and then suddenly wash ashore:
-->'''Miguel''': And it is! It really is the map to El Dorado! *he pants with excitement*
-->'''Tulio''': ...you drank the seawater, didn't you?
* As quoted, the episode "How the West was Fun" of [[TheMarvelousMisadventuresOfFlapjack Flapjack]]. The [[DisneyAcidSequence full sequence]] is mildly horrifying.

[[/folder]]

[[folder:Webcomics]]
* Webcomic/EightBitTheater: [[http://www.nuklearpower.com/2006/07/25/episode-724-somewhere-beyond-the-sea-my-elder-god-stands-on-golden-sands/ After the Light Warriors go down in a submersible]], Black Mage goes nuts in an ApocalypticLog detailing how the others also went mad weeks prior, [[CthulhuMythos along with illustrations of tentacled deep-sea creatures]]. Cut to the others asking him to stop narrating, and that they've only been there for ''less than three hours''.
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[[folder:Real Life]]
* One of the most infamous examples is the claim that sailors in previous centuries thought they had seen mermaids while at sea. It's generally assumed that they actually just saw manatees who feed their young in a manner that resembles a human female breastfeeding her baby. Still, you have to pretty insane to confuse a Manatee with a human female.
** Well, that or... ahem... [[SituationalSexuality very desperate.]]
*** Though Columbus wrote in his log "I have seen the mermaids, and they are not so beautiful as tales tell."
[[/folder]]
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