The Sky Is an Ocean

Sister Trope of Space Is an Ocean. 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, the metaphor can easily be taken a little too far (although the presence of gravity might explain parts of it). Often runs on the Rule of Cool.

May involve:
 * Airborne Aircraft Carrier
 * Cool Airship
 * Floating Continent
 * Flying Seafood Special
 * Sky Pirates
 * Sky Surfing
 * Space Whale, just in the sky instead.
 * World in The Sky
 * Those Magnificent Flying Machines

Contrast Water Is Air, Sand Is Water.

Anime and Manga

 * One Piece 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 Super Drowning Skills.
 * 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 Super Drowning Skills effect, since it's found in Seastone which can de-power Devil Fruit users.
 * Simoun, pretty much all of it.
 * In the Ah My Goddess manga, the Schroedingers swim through the air... so it might not completely count. Still evokes the trope, though.
 * Castle in The Sky
 * Last Exile
 * 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.

Comic Books

 * The Cross Gen series Meridian was set in a world of floating islands and airships.

Film

 * Sky Captain and The World of Tomorrow

Literature

 * The Dreamlands of HP Lovecraft'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 Xanth sits among the clouds, upon which (magical, one presumes) boats can be floated.
 * In The Integral Trees by Larry Niven, 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.
 * Older Than Radio: Sir Arthur Conan Doyle penned a short SF piece entitled The Horror of the Heights featuring an aviator who has a nasty run in with a swarm of flying jellyfish.
 * Edgar Rice Burroughs uses this trope throughout his Martian tales, especially when The Hero is being chased by Sky Pirates.
 * Karl Schroeder's "Virga" series takes place inside a Hollow World filled with air, where people, ships, and entire cities float around.

Live Action TV

 * In A Christmas Carol of Doctor Who, the sky above a planet was full of fish (including sharks).

Video Games

 * The entire point of Skies of Arcadia. Hell, different parts of the sky are actually called "oceans" - you start in Mid Ocean and go out from there.
 * Yet the Sky Pirates are still called "sky pirates", despite no other kind of pirate existing.
 * Ecco the Dolphin: 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 GIANT FLYING JELLYFISH.
 * Defender of the Future had huge floating water globes, floating water tubes, and non-floating-but-still-in-the-sky squid.
 * Bahamut Lagoon.
 * Final Fantasy XII 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?
 * Final Fantasy Crystal Chronicles: 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 Super Mario Bros 3. In the game Super Mario Galaxy however, Bowser actually upgrades them all so they can fly through outer space.
 * Done wonderfully in Baten Kaitos.

Western Animation

 * Due to the fact that it's set in a hovering planet, The Mysterious Geographic Explorations of Jasper Morello uses this trope heavily. There are flying fish, Sky Pirates and floating islands, and the main characters are aeronauts who use airships to travel through "uncharted air".
 * The flying pirate ship in Peter Pan definitely evokes this.
 * Skyland
 * Tale Spin eats sleeps and breathes this trope

Real Life

 * When the Captain or First Officer of your airliner 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! Airport!
 * Specifically Sky Harbor airport in Phoenix.
 * Not to mention terms in other languages, such as "embarque" and "desembarque" in Portuguese, used for boarding and unboarding airplanes (as well as busses, subway, train and other transportation).
 * 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 slow moving but there interiors often wouldn't look out of place on an ocean liner. The Hindenburg for example had private passenger quarters, public areas, a mess hall, and even an old ship's wheel used for steering in the cockpit.