[[quoteright:330:[[VideoGame/SkiesOfArcadia http://static.tvtropes.org/pmwiki/pub/images/arcadia_ships.jpg]]]]

SisterTrope of SpaceIsAnOcean. In this case, it's the sky being used to make visual/stylistic parallels to the ocean, but the same basic principles apply. As with space, [[{{Metaphorgotten}} the metaphor can easily be taken a little too far]] (although the presence of gravity ''might'' explain parts of it). Often runs on the RuleOfCool.

'''May involve:'''
* AirborneAircraftCarrier
* CoolAirship
* FloatingContinent
* FlyingSeafoodSpecial
* SkyPirates
* SkySurfing
* SpaceWhale, just in the sky instead.
* WorldInTheSky
* ThoseMagnificentFlyingMachines

For more info on the RealLife lumbering battleships and luxury liners that ply the skies, see our UsefulNotes on [[PlaneSpotting military aircraft]] and [[UsefulNotes/{{Airships}} airships]]. Contrast WaterIsAir, SandIsWater.
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!!Examples:

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[[folder:{{Anime}} and {{Manga}}]]
* ''OnePiece'' takes it literally in the Skypeia arc, where the clouds are considered an ocean. Luffy tests whether it works like in the world below...and yeah, it still gives him SuperDrowningSkills.
** It's explained that the sea and island clouds are created when an element called 'pyrobloin' (ejected from volcanoes into the sky) reacts with water vapor. The type of cloud created depends on the density of the water vapor. The pyrobloin accounts for the SuperDrowningSkills effect, since it's found in Seastone which can de-power Devil Fruit users.
* ''{{Simoun}}'', pretty much all of it.
* In the ''Manga/AhMyGoddess'' manga, the Schroedingers swim through the air... [[spoiler:but it's mainly in a conceptual space]] so it might not completely count. Still evokes the trope, though.
* ''CastleInTheSky''
* ''LastExile''
* Discussed in ''{{Trigun}}'': Vash compares the large open sky to "the deep blue sea"... even though he's never seen the sea or even been close to a large water point.
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[[folder:Comic Books]]
* The Creator/CrossGen series ''Meridian'' was set in a world of floating islands and airships.
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[[folder:Film]]
* ''Film/SkyCaptainAndTheWorldOfTomorrow''
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[[folder:Literature]]
* The Dreamlands of Creator/HPLovecraft's Cthulhu Mythos feature boats that float on the sky and can sail to the moon.
* ''Airborn'' has Sky Pirates and an airship that's basically a luxury cruise liner.
* The Nameless Castle in ''Literature/{{Xanth}}'' sits among the clouds, upon which (magical, one presumes) boats can be floated.
* In ''The Integral Trees'' by Creator/LarryNiven, which is set in a thin, orbiting band of breathable air the sky literally is an ocean, since there is no actual planet one can set foot on.
* OlderThanTelevision: Sir Arthur Conan Doyle's 1913 scifi short story "The Horror of the Heights" features an aviator who has a nasty run in with a swarm of flying jellyfish.
* Creator/EdgarRiceBurroughs uses this trope throughout his [[JohnCarterOfMars Martian tales]], especially when TheHero is being chased by SkyPirates.
* KarlSchroeder's "Virga" series takes place inside a HollowWorld filled with air, where people, ships, and entire cities float around.
* In Michael Reaves' ''The Shattered World'', ships sail through the air-filled Abyss between the many fragments of a world broken into pieces. The sky/sea analogy is taken further still when its characters encounter "dragoneers", dragon-hunting equivalents of old-time harpoon whalers.
* In Literature/TheDeathGateCycle, each world is based on an element. Arianus, the World of Air, is exactly this, with elves using magical airships for transport.
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[[folder:Live Action TV]]
* In ''A Christmas Carol'' of ''Series/DoctorWho'', the sky above a planet was full of fish (including sharks).
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[[folder:Video Games]]
* The entire point of ''VideoGame/SkiesOfArcadia''. Hell, different parts of the sky are actually ''called'' "oceans" - you start in Mid Ocean and go out from there.
** Yet the SkyPirates are still called "'''sky''' pirates", [[OrphanedEtymology despite no other kind of pirate existing]].
* ''EccoTheDolphin: The Tides of Time'' has "the great sea of the sky", which includes floating islands, giant water tubes, dolphins who have evolved helium sacs to float in the air, and [[FlyingSeafoodSpecial GIANT FLYING JELLYFISH.]]
** ''Defender of the Future'' had huge floating water globes, floating water tubes, and non-floating-but-still-in-the-sky squid.
* ''VideoGame/BahamutLagoon''.
* ''VideoGame/FinalFantasyXII'' is all over this, complete with fleets, battleships, carriers, and Sky Pirates.
** Final Fantasy in general is all over this. Name one game which doesn't have an airship in it, I dare you...
** In FFIII there are cutscenes which show that said airship has OARS. Need I say more?
** ''FinalFantasyCrystalChronicles: The Crystal Bearers'' goes so far as to include a ''wake of mana'' in the shape of ocean waves trailing from behind its bigger ones.
* The airships from ''VideoGame/SuperMarioBros3''. In the game ''VideoGame/SuperMarioGalaxy'' however, [[BigBad Bowser]] actually upgrades them all so they can [[SpaceisanOcean fly through outer space.]]
* Done wonderfully in ''BatenKaitos''.
* The X game series. Space ships experience severe drag and fly at speeds of 50-400 m/s. Their greatest sensor range is something like 25 m. What they don't know is that they are all not in space but underwater. It's a boron plot, no doubt.
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[[folder:Western Animation]]
* Due to the fact that it's set in a [[WorldInTheSky hovering planet]], ''TheMysteriousGeographicExplorationsOfJasperMorello'' uses this trope heavily. There are [[FlyingSeafoodSpecial flying fish]], Sky Pirates and floating islands, and the main characters are aeronauts who use [[CoolAirship airships]] to travel through "uncharted air".
* The flying pirate ship in ''PeterPan'' definitely evokes this.
* ''{{Skyland}}''
* ''WesternAnimation/TaleSpin'' eats sleeps and breathes this trope
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[[folder:Real Life]]
* When the ''[[TheCaptain Captain]]'' or ''[[NumberTwo First Officer]]'' of your air''liner'' turns off the "Fasten Seat Belts" signs you may move about the ''cabin''. Flight Attendants were once ''stewards'' and ''stewardesses'', and they still serve food and drinks from a ''galley''. Very large airliners have upper and lower ''decks''. Aircraft are steered to ''port'' or ''starboard'' by ''pilots'' and one of the control-surfaces they use is the ''rudder''.
** Ooh! Ooh! Air''port''!
*** Specifically Sky Harbor airport in Phoenix.
** Needless to speak about ''bulkheads'' (pro walls), ''navigation lights'' (pro flight lights), ''cockpit'' (pro control room) and so on. The airspeed is measured in ''knots'' - not kilometres or miles per hour. The whole aviation terminology derives itself from maritime. The glazed see-through apertures on the fuselage are windows, though - not portholes.
** Not to mention terms in other languages, such as "embarque" and "desembarque" in both Spanish and Portuguese, used for boarding and unboarding airplanes (as well as busses, subway, train and other transportation).
** Justified since aviation terminology is based on seafaring terminology since boats came before planes.
** Until it's collapse in 1991, Pan Am Airways referred to it's airliners as ''Clippers'', with each aircraft being individually named in the style of sailing ships, with names such as ''China Clipper'' and ''Clipper Defiance''. In the US, Pan Am was originally a TropeCodifier for this trend in civil aviation, with pilots transitioning from [[ThoseMagnificentFlyingMachines leather jackets with silk scarves]] to uniforms similar to those worn by naval officers.
* While modern day aircraft my not invoke this trope that much, the airships of the early 20th century most certainly did. Not only were they large and relatively slow moving, but their massive, palatial interiors often wouldn't look out of place on an ocean liner. The ''{{Hindenburg}},'' for example, had private passenger staterooms, a bar, promenades, a double Grand Staircase (complete with a bust of Hindenburg himself), a piano lounge, a restaurant, and even an old-fashioned ship's helm used for steering in the Führergondel (what the Germans call a control car, "leader gondola").
* Santos Dumont (a Brazilian aircraft scientist) once said "The atmosphere is our ocean.".
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