It is also the only ocean not being defined by the continents around it, but by a specific current: the Antarctic Circumpolar Current (ACC).
The Earth has finally attained popular recognition for its fifth ocean, with a decision by the National Geographic Society to add the Southern Ocean around Antarctica to the four it recognizes already: the Atlantic, Pacific, Indian and Arctic oceans.
Although the designation of the frigid waters around the icy southern continent as a separate ocean has kicked around for almost 100 years and is widely used by scientists, until now it has not had popular backing.
But on June 8 — World Oceans Day — the society announced it would henceforth be labeling the Southern Ocean as the fifth ocean on its maps of our planet.
From here: Earth’s fifth ocean just confirmed | Space.