[[quoteright:320:http://static.tvtropes.org/pmwiki/pub/images/orangesea_6367.jpg]]
[[caption-width-right:320:I don't think we're on the Atlantic any more.]]

One of the quickest, easiest ways to establish an alien world as being very unlike Earth is to make its "water" some wacky colour, or give it some other unusual features or appearance. It's not always explained exactly what kind of chemicals or minerals are causing it to look this way, but regardless, it's still perfectly able to support the native flora and fauna (though [[SuperDrowningSkills that doesn't mean]] [[HazardousWater it is safe for Earthlings]]).

See also AlienSky, which serves the same purpose and may accompany it - the Earth's oceans are the same colour as the sky due to similar refraction, so if the sky and sea don't match you must be someplace ''exceptionally'' alien.

Compare WaterfallIntoTheAbyss. Contrast AllPlanetsAreEarthLike.

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!Examples:

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[[folder: Anime and Manga ]]

* The oceans of Namek in ''Anime/DragonBallZ'' are green (and the vegetation is blue).
* Used in the ''RebuildOfEvangelion'' movies to highlight the ecological damage to Earth post-Second Impact: the sea has literally turned red with blood.

[[/folder]]

[[folder: Literature ]]

* In ''Literature/TheSpaceTrilogy'', the waters of Malacandra have the peculiar quality of very pointy standing waves and are literally blue (not just reflective of the sky); the seas of Perelandra, on the other hand, are ''orange'', and have floating mats of seaweed on which 'land-dwelling' life grows instead of islands.
* The Amoebic Sea, of WayneBarlowe's SpeculativeDocumentary {{Expedition}} (and its adaptation AlienPlanet) is actually a living gelatinous colloid of microorganisms. The edge of the sea towers over the surrounding beach.
* ''Literature/{{Solaris}}'' depicts a strange planet completely covered by a multicolored sea, which is actually one living, sentient organism. There were two film versions of the book which also contained this sea.
* The ''Literature/{{Dragaera}}'' series reveals in passing that the ocean is orange, although it's unclear if this applies to the whole thing or just the portion that's blanketed by the Overcast.
* The ''Literature/{{Monster Blood Tattoo}}'' series, set in a bio-alchemical-punk fantasy world, has strongly acidic, multicolored oceans that are the result of exotic salts from the sea floor dissolving into the water. Swimming in it is unhealthy: in half an hour you will have a really bad rash, and over an hour and a half will kill you. Not to mention that there are colossal monsters and kraulschwimmen that stalk the sea lanes and prey on ships and sailors.
* In ''{{Literature/Animorphs}},'' the Yeerk homeworld is covered with huge lakes of what look like melted lead, where the Yeerks live in their unhosted state. Leera, meanwhile, is mentioned having oceans so clear that you can see for miles.
* In Creator/SergeyLukyanenko's third novel of ''Literature/ALordFromPlanetEarth'' trilogy, aptly named ''Sea of Glass'', all bodies of water on a remote uninhabited planet appear to be made of dust or sand. In fact, the water is perfectly consumable and hydrating, but it only turns to liquid when ingested by someone, although it does feel a bit like eating sand at first. It's a strange curiosity that no one has bothered to study since [[spoiler:humanity is too busy fighting a war with a BlueAndOrangeMorality enemy]]. The final CombatByChampion takes place on this planet on the shore of a "sand" sea. [[spoiler:The protagonist manages to deliver the killing blow, and then both his and the enemy's blood mixes and contacts the "water", which starts a chain reaction that turns the entire sea into regular liquid water]].
* In the Literature/SkylarkSeries, the planet Osnome has literally blue oceans. This is because they are an ammoniacal copper sulphate solution - copper being exactly what the protagonists are in search of.

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[[folder: Live Action TV ]]

* In a scene in ''Series/StarTrekDeepSpaceNine'' various characters compare the tint of the oceans on their homeworlds. Earth's are blue. Bajor's are green. Trill's are purple.
** The Great Link resembles a reddish ocean, but it's actually billions of Changelings in [[ShapeshifterDefaultForm liquid form]], intermingling with each other.
* The ''Series/DoctorWho'' story "Mindwarp" opens with the TARDIS landing on the beach on a planet where the ocean is bright pink.
** "The Keys of Marinus" attempted it first: Marinus had sands of glass and seas of sulfuric acid.

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[[folder: Tabletop RPG ]]

* ''TabletopGame/CallOfCthulhu''
** Campaign ''The Fungi from Yuggoth'', adventure "Halls of Celaeno". The fourth planet of the star Celaeno (in the Pleaides) has a grey ocean.
** ''Fragments of Fear (second Cthulhu Companion)'', adventure "Valley of the Four Shrines". The {{PC}}s can use a CrystalBall-like device to view the gray Lake of Hali where Hastur the Unspeakable lives (a planet circling the star Aldebaran).
* ''TabletopGame/DungeonsAndDragons''
** Adventure Q1 ''Queen of the Demonweb Pits''. One of the alternate worlds the {{PC}}s can visit from Lolth's Web is a planet with a pink ocean.

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[[folder: Video Games ]]

* While never explicitly stated, the oceans of Age 233 from ''VideoGame/{{Riven}}'' are known to be highly acidic. For one thing, Gehn collects his water from a giant bowl on the roof. For another... well, [[http://images.wikia.com/egamia/images/9/9a/Age_233.jpg try and guess the range of the tidal zone]].
** From the same series (and game), Riven has water that is more of a gelatinous colloid suspended in a mesh of microorganisms that are noticeably afraid of heat.
** Multiple Ages - Spire, Relto, and Kadish Tolesa among them - have a 'sea' consisting of a thick layer of fog.
** The enormous lake surrounding Ae'gura in ''VideoGame/{{Uru}}'' was filled with algae that caused it to glow in the dark 3/5 of the time, producing a day/night cycle. Until the algae were wiped out, of course.
** The 37th Age has a sea filled with 'dark currents'; when the seawater mixes with the freshwater that flows from the rivers of the one charted island, it releases a thick mist which the inhabitants worship as The Whiteness.
** Torus' twin "seas" are connected through the hole in the centre of the ring; driven by a force of unknown origin, the water on one side drains through an enormous whirlpool and into an enormous fountain on the other, where it gushes into the upper atmosphere, evaporates, breezes to the 'edge' of the ring, and condenses and falls as rain.
* In ''{{Populous}}'', four of the terrains have differently-colored substances that function the same as water in the others: Rock & Lava has red lava, Bit Plaius has floating letters spelling [[CreatorCameo BULLFROG,]] Cake Land has caramel, and Silly Land has a checkerboard pattern.
* Natural seas in ''VideoGame/{{Spore}}'' can be blue, green, or red.
* The Special Stages in ''SonicCD'' are set on islands on other planets, each with a different color ocean.
* The Jade Sea of GuildWars is literally made of Jade due to Shiro transforming a normal sea with the Jade Wind. The waves are now frozen in place in the form of pure Jade as is the maelstrom known as Unawakening Waters.
** Bizzarely fish such as kraken, carp, rays, jellyfish and crustacians still live on the Jade Sea's surface though have(with the obvious exception of crustacians who ''already'' have legs) sprouted legs(carp and rays) or have taken to floating(kraken and jellyfish).

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[[folder: Web Original ]]

* The various [[SingleBiomePlanet Lands]] in ''Webcomic/{{Homestuck}}'' feature rivers and seas made of things like magma, oil, blood, paint, and tea.
* In ''Literature/{{Phaeton}}'' Carbonia has seas of amniotic fluid like material, which makes it oceans breathable to humans, interestingly enough the air is toxic to humans as well.

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[[folder: Western Animation ]]

* ''PiratesOfDarkwater'' had the beautiful, bizarre, and geologically unstable alien water-world of Mer.

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[[folder: Real Life ]]

* Saturn's moon Titan has [[http://en.wikipedia.org/wiki/Lakes_of_Titan seas composed of a mix of ethane and liquid methane]] rather than water, and reflect the orange-brown sky. Needless to say, it is not an environment that would be well suited for human life.
* Jupiter's moon Europa and Saturn's moon Enceladus are both suspected of having massive oceans hidden under miles of surface ice.
* Earth can give the impression of not being itself in places, too:
** [[http://en.wikipedia.org/wiki/Lake_Tahoe Lake Tahoe]] is noted for its [[http://www.flickr.com/photos/23155134@N06/5759049867/ unusual color]]. The water appears to change from gold to green to blue to purple depending on the depth.
** Similarly, [[http://www.marinelifephotography.com/diving/california/california.htm Emerald Bay]].
** The Laguna Colorada in Bolivia is a red lake. [[http://www.odditycentral.com/pics/the-red-lake-of-bolivia.html No, really.]]
** [[https://polymathically.wordpress.com/2014/12/11/algae-on-a-gray-sand-beach/ Ho'okena Beach on Hawaii's Big Island]] is one of the few ''gray'' sand beaches in the world.
** There is also the Lake Retba or Lac Rose in Senegal and this lake [[http://www.buzzfeed.com/babymantis/lake-retba-senegals-pink-lake-1opu is]] [[http://www.senegal-online.co.uk/pink-lake.htm pink]]. The color is caused by strange bacteria and, oddly, salt content.
* Fairly recently, in 1980-90s palaeontologists asked themselves: what were the ancient seashores like? Real ancient, pre-Cambrian and early Palaeozoic. Current consensus is that without higher plants wind and water erosion went really fast, and land was very flat low plains with occasional vertical rocks. There was no such thing as riverbeds, water flowed into seas as an even layer all over the shoreline. Sediments were carried far into the sea, resulting in far stretches of shallow waters. There was no distinct border between sea and dry land, no shoreline, just kilometres of shallow pools and mud, that got slightly wetter at high tide. Creatures like modern mudskippers would thrive in such environment.
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