Sea Currents

Sea currents are forces of major importance in the world of One Piece. Since the world is predominantly covered with water, currents are used to propel ships to certain destinations at greater speed. Currents are usually created by changes of temperature in the water, and difference in salinity (the concentration of salt) levels, though there are some exceptions. The only place where you can't find sea curents is in the Calm Belts. It is said that all currents eventually connect to ach other, rising up and down like a dragon.

Surface Currents
Surface currents are currents found in the warmer waters closer to the suface, and are quite fast moving.

Deep Currents
Deep currents are currents found in the cooler waters closer to the sea bed, and are quite slow moving. It is said that if a ship enters the wrong deep current, it can be trapped in the current for over two thousand years before it can reach the sunlight.

Knock Up Stream
It is considered as a natural disaster by most, but Nami describes it as a powerful current going straight up. It is created when water gets trapped in an underwater cave, where it is super-heated by lava beneath it, until the pressure gets too much, causing the sea to explode upwards.

Tarai Current
The Tarai current, or the tub current, is a massive whirlpool that connects the three major World Government facilities.

Downward Plume
Described as a massive "underwater waterfall", it is located near a winter island that makes up part of the Red Line. It is used to get to Fishman Island more quickly.