Which I am fine with. Calling it "South/Southern Island" would be ridiculous, however.
Antartica is a romanized form of "opposite to the Arctic/Opposite of the North". Again, the name makes all the difference in comparison to the meaning. If they called it Anti-North, would that truly sound right? Or would you think our ancestors were on crack?
Right you want something better, look at Australian States
We have Western Australian, why cause it is the western most state
South Australia, yup you guessed it. Oddly enough not the southern most state, but certainly a state in the south of Australia.
Northern Territory, no prizes for why.