Complex sentence: Most of the islands are located near the southeast edge of the largely submerged continent centred on New Zealand called Zealandia, which rifted away from Australia 60-85 million years ago and from Antarctica between 130 and 85 million years ago.
Split into simpler sentences: Most of the islands are located near the southeast edge of the largely submerged continent centred on New Zealand called Zealandia. It sank after rifting away from Australia 60-85 million years ago and from Antarctica between 130 and 85 million years ago.