Southern Ocean

The Southern Ocean, also known as the Antarctic Ocean or South Polar Ocean, is the oceanic division completely in Earth's southern hemisphere encircling Antarctica, comprising the southernmost waters of the World Ocean south of 60° S latitude. However, the Southern Ocean's northern boundary is not precise. Instead, the Antarctic Convergence, an ocean zone which fluctuates seasonally, separates the Southern Ocean from other oceans. This dynamic, natural boundary is formed by the convergence of two circumpolar currents, one easterly flowing and one westerly.

The Southern Ocean is another name for what have traditionally been considered to be the southernmost portions of the Pacific, Atlantic and Indian Oceans. It is the fourth largest of the five principal ocean divisions and the latest to be defined, having been accepted by a decision of the International Hydrographic Organization (IHO) in 2000, though the term has long been traditional among mariners. The Southern Ocean had been included in IHO's Limits of Oceans and Seas second edition (1937), then dropped from the third edition (1957), only to be reinstated in the fourth edition (which has yet to be formally promulgated due to a number of unresolved disputes). This change reflects the recent findings in oceanography of the importance of ocean currents.