text: was the southern ocean originally called the antartic ocean.? and if so when and why was it changed?  i'm sure when i was at school many years ago it was called the latter! the southern ocean is the world's fourth largest ocean 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  before the year 2000, it was known as the antarctic ocean, as you stated.