Why is the southern boundary of the Indian Ocean debated?

The southern boundary of the Indian Ocean is considered debated because there is no universal agreement on where it ends and the Southern Ocean begins.1

While many researchers and authorities define the southern limit at latitude 60° S—recognizing the distinct waters of the Southern Ocean south of that line—other authorities maintain that the Indian Ocean extends all the way to the Antarctic coast. This lack of consensus persists because defining oceanic limits in open water is complex, and different scientific or geographical conventions prioritize varying criteria for boundary placement.12