Blue World

One Piece takes place on an unidentified fictional world, nicknamed Blue World.

The One Piece world is definitely not our Earth. This gives the author a lot of freedom to create his own world. In Chapter 392, a Geocentric model of the One Piece world with 6 satellites or planetoids (which includes their world's moon) can be seen at Ohara's Tree of Knowledge. Their world also sits on a rough angle of about 24-25 degrees, the same angle as the earth.

The first thing that needs to be mentioned is the time when the story takes place. Since One Piece is a pirate adventure, the age in the story resembles the colonial times of the real world. Of course there´s lots of differences to the real world here and there, but the ages can roughly be compared to each other.

In the world of One Piece, there seem to be three big different kinds of environments in which everyone lives in. The first is the Blue Sea, which is the massive ocean that covers most of the world of One Piece. The next one is the Cloud Sea which as the name indicates is an environment in the sky. The third one hasn't been given a official name so far since it only appeared in a side story, but since the surface and sky environment have been mentioned, the last one is the Sea Floor.

The Blue Sea
The Blue Sea, which is where the bulk of the storyline takes place, consists of one large continent, one long chain of islands, and four seas that make up two larger oceans. The continent is called the Red Line, the big chain of islands is called the Grand Line and the four seas are called North Blue, South Blue, East Blue and West Blue.

The Four Blues
As explained above, North Blue, South Blue, East Blue and West Blue make up the four seas of the blue world. Within each Blue, sea travel works as it does in the real world. You can sail to any destination you want with a regular compass. However getting from one Blue to another is much more difficult. The reason is because not only the Red Line separates the two oceans, but also because the seas within one ocean are separated by a large sea route called the Grand Line as well as two Calm Belts.

Grand Line
The Grand Line is the ocean current that follows an imaginary line that runs from north-west to south-east across the middle of the world and perpendicular to the Red Line. It is commonly reffered to those in the 4 Blue Seas as "the Pirate Graveyard."

Calm Belt
The Calm Belt is a sea area that surrounds each side of the Grand Line. No winds or sea currents can be found there, hence the name "Calm Belt". As a result, sailing through it is extremely difficult, especially because it is the nesting ground for the Sea Kings.

Red Line
The Red Line is the one and only continent in the One Piece world. It traverses the entire world from north to south. The Red Line separates the two oceans into four smaller seas. One of the oceans forms the two seas, East Blue and South Blue, and the other one forms the North Blue and the West Blue.

Cloud Sea or Sky Ocean
The Cloud Sea is a place that is unknown to most people in the Blue Sea. The reason for that is that the Sky Ocean is entirely made of clouds, which from the Blue Sea doesn't look like an ocean. The Sky Ocean clouds, however, are no normal clouds. There are two kinds of clouds, Sea Clouds and Island Clouds. Sea Clouds are just as water, which means that you can sail on it if you´re not to heavy to sink through it, whereas Island Clouds are dense enough to carry all kinds of things.

There are different ways to get to the Cloud Sea from the Blue Sea, however the only way that has been shown so far is the unorthodox and dangerous way in which the sailors have to take a Knock-Up Stream. In the Sky Ocean there are two known seas, the White Sea and the White White Sea.

Moon
Fairy Vearth is a legendary land that Enel mentions throughout the Skypiea arc. Enel wanted to travel to Fairy Vearth after he destroys Skypiea. For this purpose he built ship Maxim.

After being defeated by Luffy, Enel headed off to Fairy Vearth, which turns out to be the Moon. There he found a group of alien-like creatures known as Spaceys who have wings similar to like the Skypieans, which Enel befriended.