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 that doesn't mean it is safe for Earthlings). Compare to Alien Sky, which serves the same purpose - note that Earth's oceans mostly just reflect the colour of the sky, so if the two don't match you must be someplace exceptionally alien. Contrast All Planets Are Earth-Like. (Indices: Spectacle, Tropes at Sea, Tropes in Space, Speculative Fiction Tropes)
- The seas of Malacandra have the peculiar quality of very pointy standing waves; 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 Wayne Barlowe's Speculative Documentary Expedition (and its adaptation Alien Planet) is actually a living gelatinous colloid of microorganisms. The edge of the sea towers over the surrounding beach.
- The book Solaris depicts a strange planet completely covered by a multicolored sea. There were two film versions of the book which also contained this sea.
- The 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 oceans of Namek in Dragon Ball are green (and the vegetation is blue).
- Call of Cthulhu
- 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 PCs can use a Crystal Ball-like device to view the gray Lake of Hali where Hastur the Unspeakable lives (a planet circling the star Aldebaran).
- Dungeons & Dragons
- Adventure Q1 Queen of the Demonweb Pits. One of the alternate worlds the PCs can visit from Lolth's Web is a planet with a pink ocean.
- In a scene in Star Trek: Deep Space Nine various characters compare the tint of the oceans on their homeworlds. Earth's are blue. Bajor's are green. Trill's are purple.
- The Doctor Who story "Mindwarp" opens with the TARDIS landing on the beach on a planet where the ocean is bright pink.
- While never explicitly stated, the oceans of Age 233 are known to be highly acidic. For one thing, Gehn collects his water from a giant bowl on the roof. For another... well, 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 f 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 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 BULLFROG, Cake Land has caramel, and Silly Land has a checkerboard pattern.
- Natural seas in Spore can be blue, green, or red.
- The Special Stages in Sonic CD are set on islands on other planets, each with a different color ocean.
- Obligatory Homestuck examples - the various Lands feature rivers and seas made of things like magma, oil, blood, paint, and tea.
- Pirates Of Darkwater had the beautiful, bizarre, and geologically unstable alien water-world of Mer.
- Saturn's moon Titan has 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.
- Earth can give the impression of not being itself in places, too:
- Lake Tahoe is noted for its unusual color. The water appears to change from gold to green to blue to purple depending on the depth.
- Similarly, Emerald Bay.
- The Laguna Colorada in Bolivia is a red lake. No, really.
- There is also the Lake Retba or Lac Rose in Senegal and this lake is pink. The color is caused by strange bacteria and, oddly, salt content.
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