A fairly common feature in near-future works is cities built on artificial islands in the middle of the ocean. Often they are built to alleviate overcrowding on land, especially when GlobalWarming causes sea levels to rise and envelop coastal cities, but just as often they are sites for {{Mega Corp}}s to do things that may or may not exactly be "legal" in most conventional nations.

Related to UnderwaterCity, which is when the colony is under the water instead of on it. Likely to also be a CityOfCanals.
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!!Examples:

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[[folder: Anime & Manga ]]

* ''[[Manga/GhostInTheShell Ghost in the Shell: Man-Machine Interface]]'' (the manga) features Poseidon Industrial's artificial island city, where Motoko Aramaki's real body is typically stored.
** The second film has an android manufacturer that bases its factory on a ship [[spoiler:because they're dubbing the ghosts of young girls into their robots]].
* The conclusion of the Enies Lobby arc in ''Manga/OnePiece'' shows turning the CityOfCanals Water Seven into this is mayor and shipwright Iceburg's next big project.
* Neo Venezia in ''{{Anime/ARIA}}'', naturally, since it's a replica of Venice.
* The ''Anime/PsychoPass'' movie is set to take place primarily on a floating city owned by a Southeast Asian government in the Pacific called Shamballa.

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[[folder: Film ]]

* In ''Film/{{Waterworld}}'', since all known land has been covered by water most people live in "atolls" made from scrap metal. As well as traders who live on boats and the "smokers" who are based on the Exxon Valdez.
* In ''Franchise/StarWars'', the populace of the water-world Mon Calamari live in giant floating cities. One half is above water for the Mon Cals and air-breathing visitors, one half underwater and flooded for the Quarren.

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[[folder: Literature ]]

* Creator/DavidBrin's novel ''Literature/{{Existence}}'' has artificial islands popping up as sea levels rise. However most of them are resorts for the super-rich or havens for questionably legal biotech experiments. China has a "shoresteading" program for desperate people to try and make the upper levels of flooded mansions in what used to be Shanghai liveable.
* Creator/GordonRDickson's ''Home From the Shore''
* Creator/NealStephenson's ''Literature/SnowCrash'' has "Rife's Raft", a gigantic, cobbled-together collection of floating garbage in the Pacific Ocean inhabited by huge numbers of refugees, mostly from Asia.
* DavidDrake's ''Literature/TheLordOfTheIsles'' series includes a vignette in the first book in which Sharina, Nonus, and some useless nobles spend a few days on the Houseboats of the Sea People. They spend their entire lives at sea and live in large structures crafted largely from whale.
* ''Literature/NineteenEightyFour'' repeatedly mentions military installations called "floating fortresses" that are apparently under construction, which dwarf the ordinary battleships that were their inspiration -- but never explains what they are.
* In ''[[Literature/{{Gor}} Raiders of Gor]]'' we meet the Caste of Rencers, who live in a delta connecting a great river and the sea, gathering rence[[note]]a multi-purpose plant used for making paper, rope, utensils, cloth, and food[[/note]] for trade. They live in small villages built on floating rafts of rence. As the rence rots away underwater they weave new layers on top.
* The Skeezers in ''[[Literature/LandOfOz Glinda of Oz]]'' live in a [[DomedHometown city]] suspended over the middle of a lake. In times of danger they can magically submerge the entire city for protection, turning it into an UnderwaterCity.
* The pirate city of Armada in ''Literature/TheScar'' takes this trope UpToEleven, being built of thousands of ships, large and small, of every conceivable design roped together en masse.
* ''Literature/SaturnsRace'' takes place on an island grown from accreted sea chemicals ('seament').
* Thule from ''Literature/ArcticRising'' is a collection of ships and oil platforms attached to the last few bits of Arctic sea ice. Later, several of them decide to go their own way.

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[[folder: Live Action TV ]]

* Atlantis, from ''Series/StargateAtlantis'' (in addition to being capable of becoming an UnderwaterCity should the need arise).

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[[folder: Tabletop RPG ]]

* Classic ''TabletopGame/{{Traveller}}'' supplement ''The Traveller Adventure''. The planet Heguz is an [[SingleBiomePlanet Ocean Planet]]. It has had two colonies, both set up on large floating bases. Both colonies mysteriously disappeared without a trace.
* ''{{Shadowrun}}'': Proteus Corp built a number of "arkoblocks" (floating arcologies) off the coast of Japan.
* One of the {{Mystara}} modules for Basic/Expert/etc DungeonsAndDragons features a floating city built on giant wooden platforms, kept above water by an enchanted idol that makes everything linked to it unsinkable.

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[[folder: Video Games ]]

* A major gameplay element of ''VideoGame/SidMeiersAlphaCentauri'', as any faction can create sea based settlements as well as the standard land based ones, in contrast to the VideoGame/{{Civilization}} series where only land based cities are permitted. The Nautilus Pirates faction starts the game with such a settlement and can create an ocean empire faster than the others.
* Frequent in RealTimeStrategy games that involve naval combat (most ''VideoGame/CommandAndConquer'' titles, for example): The ship-building structures are constructed directly at sea.
** Then there's the Black Tortoise from ''VideoGame/CommandAndConquerRedAlert3'', a huge floating fortress.
* ''VideoGame/{{Brink}}'' is set aboard The Ark, an experimental floating colony designed to be completely self sufficient.
* ''VideoGame/KnightsOfTheOldRepublic'' has the planet of Manaan with the native water-breathing Selkath, which is covered entirely with water except for Ahto City, which is built on the surface of the ocean to accommodate visitors.
* In ''VideoGame/FinalFantasyX'', during the Shoopuf ride you learn about the city built over the ocean, which was built just because it could be. Needless to say, it got destroyed by Sin and sank to the bottom.
* ''VideoGame/ResidentEvilRevelations'': Terragrigia
* {{Syndicate}} (2012) has the city of La Ballena, which is owned by the Caymen Global syndicate.
* ''[[VideoGame/TearsToTiara2 Tears to Tiara 2]]'' has Tartetos, an AdvancedAncientAcropolis that combines aspects of {{Atlantis}} and [[UsefulNotes/PreColumbianCivilizations Tenochtitlan]].

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[[folder: Webcomics ]]

* ''Webcomic/{{SSDD}}'' has the Britannia, a massive ship built on an iceberg that England's wealthy fled to when the Anarchists took over.
* In ''Webcomic/TheKennyChronicles'' Tarnekis, genetically engineered [[PettingZooPeople human-animal hybrids]] are largely forced to live on converted cruise ships. The sequel series, ''Ferrets vs. Lemmings'' takes place on an artificial island.

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[[folder: Western Animation ]]

* In a FlashForward episode of ''WesternAnimation/TheSimpsons'', Homer lives in an undersea apartment.

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[[folder: Real Life ]]

* Certain groups such as [[http://www.seasteading.org/ The Seasteading Institute]] and [[http://www.blueseed.co/ Project Blueseed]] intend to do this in real life.
* The unrecognized micronation [[http://en.wikipedia.org/wiki/Principality_of_Sealand Sealand]] is based on one of the [[http://en.wikipedia.org/wiki/Maunsell_Sea_Forts#Maunsell_sea_forts Maunsell Sea Forts]] built during WWII.
* Frequently seen in nations with sea access and not enough space for new buildings (Japan, Singapore, etc.) as well as countries with an influx of wealthy tourists and investors (Dubai, Bahrain...).
* Venice, although it's not in open sea, is probably the better known example we have today.
* Tenochtitlan, capital city of the Aztec civilization, was mostly built of "floating gardens" constructed around islands in a large lake.
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