Land of OOO

The Land of Ooo is the main setting of Adventure Time, and is the home of Finn and Jake, along with all of their friends and foes. It is divided into many different kingdoms, of which the most prominent are the Ice Kingdom, Candy Kingdom, Wildberry Kingdom, Lumpy Space, Fire Kingdom, and Cloud Kingdom. There are also many geographical areas not known to be part of any kingdom, such as the Evil Forest and the Bad Lands.

Map
Two different official maps of the Land of Ooo were released by Frederator Studios along with the original Adventure Time pitch documents: the and, both seen in the gallery below. Of these, the black-and-white one drawn by Ghostshrimp is probably more accurate for several reasons:
 * 1) Its general shape matches the aerial view of Ooo seen in "Business Time" (see picture in gallery below).
 * 2) A slightly modified version of this map appeared on Princess Bubblegum's hologram map in "The Other Tarts."
 * 3) On the black-and-white map, the names of certain places match up with the names used in the show and by its creators, while some of the names on the color map do not.

Map Only locations
The two official maps show many locations that have never been mentioned or seen on the show. Nothing is known about them other than what appears on the maps.

On the color map, a Mystery Temple appears on an island off the east coast of Ooo. It resembles a Mesoamerican pyramid. Also on the color map, the Fire Kingdom is labeled "Burning Lands" and the Grass Lands are called the "Verdant Plains." An area called "Red Rock Cliffs" might correspond to Red Rock Pass, and a note indicates that Marceline's cave is located there.

On the black-and-white map, there are many places that have never been seen in the show. To the north of Ooo is the Sea of Something, which contains a small island chain called the Shiney Isles, which appear to have crystals on them. The warrior known as the Farm hails from this island chain. On a northern peninsula near the Ice Kingdom are the Unknown Lands. In the comic, this place seems to have a purple hue. A cloud or island in the northwest corner of the map is called the Cloud Forest, which appears to be covered in clouds with trees on top of them.

The Sea of Sure Death is off the southwest coast of Ooo, near the Lost Cliffs. The map shows a dragon in the sea near there. The Isle of Steam appears off the coast of Ooo next to the Fire Kingdom. Just to the south of it is the mysterious Chicken Blood Cove. The Squid Ink Sea is to the southeast of Ooo, and features several unidentified islands. In the ocean near there is a Whirlpool of Sharks. The Floating Gems appear to be actual large gems floating in the sea on the easternmost edge of the Land of Ooo.

The Haunted Swamp is just east of the Grass Lands and north of the Spooky Forest. Strangely, in the hologram map that appeared in "The Other Tarts," it appears to be labeled as "The Haunted Swan," though this is likely an error. The Hole Near the Center of the World is, as its name suggests, a hole near the middle of Ooo.

The Hologram Temple is on the east of the Candy Kingdom.

Govnerment
Ooo exhibits a mix of democracy, dictatorship, and feudalism as well as what appears to be monarchy. Most kingdoms are ruled by one or more members of royalty, such as the Ice Kingdom and Fire Kingdom. The Grand Meeting of Ooo Royalty shows that the various rulers of Ooo meet together for discussions on a regular basis, though the topics were not revealed. Dictatorship has only been exhibited in "The Silent King" where Xergiok has taken control of the Goblin Kingdom by force. Party Pat is the chief of the Bears, but they do not display any form of government. In the episode "Paper Pete," Mildwin is the democratically elected leader of the Moldos. On Icy Saviour, Grand Holocron is the leader of the Ministry of Holographical Laws.

Ooo has also not been shown to have an army or any type of military force that protects the land as a whole. Therefore, each kingdom provides its own military or police force. The most prominent example of this would probably be the Candy Kingdom, which has fortified walls (albeit candy ones) and the Banana Guard, along with other security forces. On the other end of the spectrum is the City of Thieves, which appears to have no police force whatsoever, and all of the citizens constantly steal from one another. Benson is the leader of the Blue Gumball Army, and well his well known soldier Tom.

Religion
One of the primary deities worshiped in Ooo is Grob Gob Glob Grod. The Cosmic Owl apparently is also known as some kind of spiritual entity that appears in Croak Dreams. Ooo seems to have a number of other potentially godlike beings such as Party God and Death.

In "Holly Jolly Secrets Part I" many Christmas-themed items appear, but none of the characters show knowledge of the holiday itself (instead of Christmas, the holiday is called a day for wearing sweaters and watching secret tapes). Natasha Allegri has stated that the picture of a mother and child in Marceline's house is Mary and baby Jesus. However, there's no direct evidence that Marceline actually holds religious beliefs, and the significance of the picture has never been addressed by the characters. Since Marceline is over 1000 (and is shown in "Memory of a Memory" as having lived through some massively destructive war), if anyone remembers it would presumably be her.

In the episode "Marceline's Closet," just before Jake and Finn play Cloud Hunt, Jake mentions a central Buddhist philosophy. When asked what he is doing, Jake responds with, "Just eliminating desire from my heart. It helps to pass the time." This is the ultimate goal of the Eight-Fold path and a central idea behind the four noble truths. Jake has also stated his belief that when he "croaks" his consciousness will become one with everything while Glob tallies his deeds. This statement is a rough combination of several religious beliefs; that upon dying one's soul becomes part of everything and that one's deeds in life determine the soul's fate after death.

Leonard seems to be the only person who is catholic, and explains that he blessed God to give him immortallity.

Marsha seems to believe in immortal religion, such as vampire's culture, the lost immortral tribe, and traditions of demons and vampires. She does not believe in jewish religion but believes in Gabriel's Horn, Heaven, angels, Hell and devils.

Currency
The only currency shown in the series is dollar bills, although some store owners (Choose Goose) prefer to trade. The dollar is made in at least 2 sizes (regular and giant). The dollar was first shown in "The Enchiridion!" when Finn stole a giant dollar from an Ogre. The dollar was also seen in "To Cut A Woman's Hair," when Finn paid Simon to play for him on his violin. The dollar probably doesn't come in tiny size, because then Finn would've used a tiny dollar to pay Simon. Another appearance of the dollar came in the episode "Donny" when Mr. Bank puts himself together. Also, in the episode "Hitman," the Ice King tried to pay Scorcher not to kill Finn and Jake. Gold and jewels are also used, and even accepted as a form of tax payment in "Burning Low."

There is also a penny shown in "Sons of Mars," when Abraham Lincoln tries to use it as payment (and apparently has succeeded before). In "Guardians of Sunshine (episode)" Jake attempts to take one of the game's coins to the real world, but, much to Jake's disappointment, it turn into a penny when removed from the game. The holograms, such as Leonard, Sam, Tony, Mary, Gordan and Johnny, use holographical money and coins, which also counts as currency.

Languages
English seems to be the primary language in Ooo, though many other seem to be spoken. Some include:
 * Korean: Rainicorns speak and write in Korean; Jake and Princess Bubblegum can understand it, but speak it infrequently, if at all.
 * German: In "What Have You Done?" and "Go With Me," Princess Bubblegum spoke some German. Also, Leonard's mechanical arm in his human form says 'Made in Germany', as seen on Oil Slip.
 * French: As shown in "Incendium," the Flame King speaks some when talking to Jake. Jakes sings Alouette, a song sung in French, in "Holly Jolly Secrets Part II." Also, in "The Real You," when Finn's finger and Jake are in the Apple Classroom, a poster at the back of the room can be seen, with the month "Avril" (French for April) written on it.
 * Japanese: In "Marceline's Closet," Jake says a Japanese phrase. Jake also spoke some Japanese in "Return to the Nightosphere." And in "Gut Grinder," one of the soft people called Jake "kawaii" (meaning "cute").
 * Latin: In "Hug Wolf," the book Jake consults to discover what sort of beast Finn turns into after he was hugged by the alpha hug wolf, has its title in Latin. Also the wizard Bufo, who first appears in "Wizard," takes his name from the Latin word for toad: "bufo." The incantation used to open a portal to the Nightosphere is also in Latin. Finn also speaks quite a bit of Latin while facing off against the Gladiator Ghosts in "Morituri Te Salutamus."
 * Native American: On Leonard Puzzle, Leonard adresses the Guardian of Lightning a "haokah". It was revealed that Leonard rarely talked Native American.
 * Spanish: Marsha can perfectly speak and understand spanish. On rare occasions, she freaks out or yells in the language.

Post Apocalyptic setting

 * Main article: Mushroom War

Pendleton Ward, the creator of Adventure Time, has stated in an interview that the Land of Ooo is actually a post-apocalyptic Earth, the result of a global disaster called the Mushroom War, hence the ruined pieces of modern technology scattered across the land.[1]

It is possible that Finn may be the sole human being left in Ooo. It's also possible that the Mushroom War was responsible for killing off all the other humans, or that they mutated into the current and varied inhabitants of the planet. In "Her Parents," Lady Rainicorn's parents mention that they wanted to eat Finn because they never thought they'd get the chance to eat an actual human, implying they are either extremely rare or extinct.

For more information on Finn as the last human, see the "Status as the last human" section on Finn's article.

In "Simon and Marcy," the Land of Ooo or at least part of it used to be a pre-Mushroom War territory or country called the "Wut-Wut State" as shown on a food truck's registration plate.

In season 1 of "Adventure Time Origins," it shows the land of Ooo before the Great Mushroom War.

Trivia

 * While Pendleton Ward says the Land of Ooo is a continent,[2] Adam Muto says it is the size of a smallish island nation.[3] The maps lend more evidence to the latter.
 * The map of Ooo vaguely resembles an eagle or phoenix.
 * On the Cartoon Network advertisement for "Adventure Travel," the Land of Ooo is shown as a rolling plane rather than a continent.