Well, you'd have to know a little bit about our world first. Where I come from, the planet is all ocean. It's known as the Blue. It's divided [And here he sketches in the air a vertical circle.] longitudinally by a mountainous strip of rock that encircles the globe called the Red Line, and the Grand Line, [Horizontal circle] which runs along the equator. So the Blue is broken into quadrants - East, West, South, and North Blue. I'm from North.

The Grand Line is considered a sea of its own, due to the Calm Belts that lie on either side of it at the tropics; stretches of becalmed water with no wind or surface currents - they're sea monster nesting places. It's difficult to get into the Grand Line. There's only a few access points.

There's very little land. Most of the islands in the Grand Line? Are the size of small Caribbean islands. You're lucky if you get an island the size of that big one in Hawaii. [Yes. Someone has FINALLY looked at an atlas. He was getting tired of scratching his head every time someone brought up an Earth nation.] Outside the Line, you're better off, but there are scant few islands that are bigger than Japan or the British Isles.

So a lot of people end up on the oceans... For many different reasons it can be the only place they have left to go.