What did Captain Cook prove in the Southern Hemisphere?

As a result of Tasman’s discoveries, Australia, Tasmania and New Zealand were thought to be part of one enormous continental island. It was shown on maps of the time as Terra Australis Cognita (or Southern Known Land) separated from another to the south shown as Terra Australis Incognita (or Unknown). Captain Cook, however, proved that the former was not one but a number of huge islands. He charted the coastline of New Zealand and found it to be two islands separated from Australia by 2,400 km. He also searched for the great ‘unknown’ southern continent but finally decided that no such place existed, only a huge land mass of ice and snow which extended into both the Atlantic and Indian Oceans and which is now known as Antarctica.