The Southern Ocean, also known as the Antarctic Ocean or the Austral Ocean,[note 4] comprises the southernmost waters of the World Ocean, generally taken to be south of 60° S latitude and encircling Antarctica. As such, it is regarded as the fourth largest of the five principal oceanic divisions: smaller than the Pacific, Atlantic, and Indian Oceans but larger than the Arctic Ocean. This oceanic zone is where cold, northward flowing waters from the Antarctic mix with warmer subantarctic waters.[…]
The National Geographic Society does not recognize the ocean, depicting it in a typeface different from the other world oceans; instead, it shows the Pacific, Atlantic, and Indian Oceans extending to Antarctica on both its print and online maps. Map publishers using the term Southern Ocean on their maps include Hema Maps and GeoNova. […]
Authors using “Southern Ocean” to name the waters encircling the unknown southern polar regions used varying limits. James Cook’s account of his second voyage implies New Caledonia borders it. Peacock’s 1795 Geographical Dictionary said it lay “to the southward of America and Africa”; John Payne in 1796 used 40 degrees as the northern limit; the 1827 Edinburgh Gazetteer used 50 degrees. The Family Magazine in 1835 divided the “Great Southern Ocean” into the “Southern Ocean” and the “Antarctick [sic] Ocean” along the Antarctic Circle, with the northern limit of the Southern Ocean being lines joining Cape Horn, the Cape of Good Hope, Van Diemen’s Land and the south of New Zealand.
Source: Southern Ocean – Wikipedia