[[quoteright:330:[[VideoGame/SkiesOfArcadia http://static.tvtropes.org/pmwiki/pub/images/arcadia_ships.jpg]]]]
[[caption-width-right:330:Pirates sail the seven... skies?]]

SisterTrope of SpaceIsAnOcean. In this case, it's the sky in the atmosphere of a planet or natural satellite 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 [[UsefulNotes/PlaneSpotting military aircraft]] and [[UsefulNotes/{{Airships}} airships]]. Contrast WaterIsAir, SandIsWater.

Just pray you don't WalkThePlank. It's a long drop.



[[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.
* ''Anime/{{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.
%%* ''Anime/CastleInTheSky''
* In an episode of ''Anime/{{Doraemon}}'', the gadget-of-the-week 'Simulated Water Pump' permits the protagonists to treat air as water and 'dive' in the air, completed with FlyingSeafoodSpecial and [[CoolBoat a ship that sails in the sky]] (albeit unknowingly, it finally gets stranded on a roof).
* ''Anime/LastExile'' has airships which, due to their [[SchizoTech otherwise limited technology]], fight each other in a manner similar to pre-industrial naval ships. Furthermore, because of the planet's [[WorldShapes unusual shape]], the sky is a literal barrier that has to be crossed to get from one continent to another.
* Discussed in ''Manga/{{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.

[[folder:Comic Books]]
* The Creator/CrossGen series ''ComicBook/{{Meridian}}'' was set in a world of floating islands and airships.

[[folder:Film - Animated]]
* The flying pirate ship in ''Disney/PeterPan'' definitely evokes this.

[[folder:Film - Live Action]]
* ''Film/SkyCaptainAndTheWorldOfTomorrow''
* ''{{Film/Stardust}}'' features sailors harvesting lightning from stormclouds on a skyship that looks exactly like a sailing ship. (And a captain with... unusual interests played by Creator/RobertDeNiro.)

* Creator/JulesVerne's ''Literature/RoburTheConqueror'' may well be the TropeCodifier. Not only is the CoolPlane ''Albatross'' essentially [[http://aerostories.free.fr/dossiers/ADAV/robur.JPG a ship with propellers instead of sails,]] but the narration keeps using nautical terminology and phrases like "aerial sea," and the CoolAirship ''Go Ahead'' is actually compared with an [[SpaceWhale airborne whale]].
* 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 ''Literature/TheIntegralTrees'' 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 [[Literature/JohnCarterOfMars Martian tales]], especially when TheHero is being chased by SkyPirates.
* Creator/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.
* Creator/JimButcher's ''Literature/TheCinderSpires'' has a lot of {{Magitek}} powered skyships and aerial combat. The sky is specifically the ocean circa the Anglo-Spanish or Napoleonic Wars, and one of the main characters is {{privateer}}.
* In the {{Literature/Temeraire}} series, dragon-based aviation forms a branch of the military of many countries during the Napoleonic wars. The associate officers are given naval ranks, like cadet, lieutenant, captain, commodore, and admiral. The main character even used to be a 'naval' captain, until he became an aviator when he got a dragon egg thrown in his lap.

[[folder:Live Action TV]]
* In ''A Christmas Carol'' of ''Series/DoctorWho'', the sky above a planet was full of fish (including sharks).

[[folder:Tabletop Games]]
* There's currently an RPG in development known as Upwind. It's conceptualized as being a cross between "Disney/TreasurePlanet" and "Creator/StudioGhibli". Uncharacteristic for most RPG systems though, the game uses playing cards in place of Dice. Allowing for a more free flowing system.

[[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 "'''air''' pirates", [[OrphanedEtymology despite no other kind of pirate existing]].
* ''VideoGame/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.
* Cutscenes in ''FinalFantasyIII'' show an airship with oars.
* ''VideoGame/FinalFantasyCrystalChroniclesTheCrystalBearers'' goes so far as to include a wake of mana in the shape of ocean waves trailing from behind its bigger airships.
* 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 ''VideoGame/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.
* In the UsefulNotes/ArcadeGame ''Sky Adventure'', the FinalBoss is a flying armored galley with oars.
* ''VideoGame/GranblueFantasy'' takes place across a series of floating islands, suspended in a balance of power between [[CelestialParagonsAndArchangels four angelic Primarchs]] created by [[{{Precursors}} the Astrals]].
* ''Videogame/Pirate101'' has this to an odd sort of extreme, in that pretty much any inanimate object that would float on water seems to float on a particular horizontal plane in the air. Despite this, the players flying ship seems to have some sort of altitude control (though it's only ever used during the loading screen between zones). It's also populated by numerous [[FlyingSeafoodSpecial flying sea creatures]].

* ''{{Webcomic/Evus}}'' is set in a WorldInTheSky, so ships and [[CoolPlane pteroplanes]] fly through the Midcloud Layer. The Undercloud Layer compares to the dark, unexplored depths of the ocean.

[[folder:Western Animation]]
* Due to the fact that it's set in a [[WorldInTheSky hovering planet]], ''WesternAnimation/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".
* ''WesternAnimation/{{Skyland}}''
* ''WesternAnimation/TaleSpin'' eats sleeps and breathes this trope
* The ''Pines of Rome'' segment in ''Disney/Fantasia2000'' takes this to its logical extreme with whales swimming through the air and breaching through the [[SpaceIsAir air/stratosphere boundary]].

[[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 kept on ''course'' and steered to ''port'' or ''starboard'' by ''pilots'' and one of the control-surfaces they use is the ''rudder''. At take-off and landing, the ''cabin crew'' are told to take their ''stations''. The space for luggage is ''cargo hold'' where the payload is ''shipped'' to the destination, and the place for relieving your internal pressure is ''head''. While airplanes have fuselages, flying boats have ''hulls''. The captain, who sits in the ''cockpit'', will do the ''navigation'' and plot the ''bearing'' and ''course'' for the ''autopilot''.
** Ooh! Ooh! Air''port''!
*** Specifically Sky Harbor airport in Phoenix.
*** ''Port'' Columbus International Airport in Columbus, Ohio
*** ...where you ''embark'' and ''disembark'' the passengers.
** 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, with ''cruising speed'' usually being around 450 to 500 kn. The whole aviation terminology derives itself from maritime. The glazed see-through apertures on the fuselage are windows, though - not portholes.
** The navigation lights are exactly the same as on maritime vessels - red on port wing, green on starboard wing and white at aft. When the engine is on, strobe beacon is lit on both sides of the fuselage (corresponds to the white motoring light of maritime vessels). Actually flying boats, hovercraft, ground effect planes and floatplanes ''are'' included in the international maritime navigation light rules.
** The Right of the Way Rules are ''exactly'' the same in the sky as at the sea. Supplied with the rule that the one who has less altitude has the right of the way.
** 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 its 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.
** Giving the airplanes individual names (like ships have) instead of just referring them as their radio calls is customary amongst several airlines.
* 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. UsefulNotes/TheHindenburg, 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").
* Alberto Santos Dumont (a Brazilian aircraft scientist) once said "The atmosphere is our ocean.".
** This reflected the design philosophy of the time. Early semi-aircraft like Santos Dumont's designs had only a rudder for control, and mounted propellers with much the same design as those used by naval craft, as opposed to the 3-axis control and airfoil-shaped propellers pioneered by the Wright Brothers.
* Some planetary climatologists find it easier to model the oceans as simply a lower, denser region of the atmosphere when considering its role in water cycles and global temperature patterns.
* Many aviators refer their airplanes simply as ''ships''.
* Subverted in ''naval'' aviation where the flyers are '''aviators'''. That is because the term "pilot" has a distinct maritime meaning.
** The word "pilot" in particular is so closely associated with air pilots that hearing it [[HaveAGayOldTime in its original sense]] can seem odd. When [[Theatre/RomeoAndJuliet Romeo]] says "I am no pilot", he's obviously not talking about [[SchizoTech flying a Cessna in the Renaissance]], but it still sticks out.
* TruthInTelevision (sort of) for large planets as Jupiter, Saturn, Uranus, Neptune, and their extrasolar equivalents where their atmospheres blend smoothly with either oceans of liquid hydrogen (Jupiter, Saturn, and their kind) or exotic forms of a mixture of water, methane, and ammonia (Uranus, Neptune, and alike).