Zealandia, also known as the New Zealand continent, is an almost entirely submerged mass of continental crust that sank after breaking away from Gondwana about 100 million years ago. It extends from near the Chatham Islands in the east to west of New Caledonia and north to south of Stewart Island. About two-thirds of Zealandia’s area is under the Pacific Ocean, with a maximum depth of 8200 m (26900 ft).
The remainder consists of several large islands including New Zealand’s North Island and South Island, as well as Banks Peninsula which form part of Canterbury Province. The Cook Strait between North Island and South island is so named because it was first discovered by Captain James Cook during his 1769 circumnavigation of New Zealand.
Zealandia’s main landmass includes four biogeographic regions:
the eastern region around the Chatham Islands;
the northern region extending from Three Kings Islands to Auckland;
the central region covering Wellington and Marlborough; and
the southern region encompassing Fiordland, parts of Otago, and Stewart Island/Rakiura.
Each has distinct geology, climate, flora and fauna.