How the ACC defines the Southern Ocean

While the other oceans are defined by the continents that fence them in, the Southern Ocean is defined by a current: the Antarctic Circumpolar Current (ACC), which surrounds it.

The ACC flows from west to east around Antarctica. Inside the ACC, the waters are colder and slightly less salty than ocean waters to the north.

Furthermore, the ACC helps keep Antarctica cold and the Southern Ocean ecologically distinct, with thousands of species living only there.