Who discovered Australia and when?
James Cook sailed along and mapped the east coast Australia in 1770, which he named New South Wales for his country Great Britain.
However, Cook by no means discovered Australia, nor was he even the first Englishman to land on its shores. That was done by William Dampier in 1688, and his opinions of Australia ("New Holland" as it was then known) were less than complimentary.
Aborigines had been in Australia for thousands of years, and Malay and Macassan traders had been landing on the far northern coast, collecting sea slugs to trade with China, for many years.
Willem Jansz/Janszoon was a Dutchman who was seeking new trade routes and trade associates. He became the first recorded European to step foot on Australia's shores on the western shore of Cape York Peninsula, on 26 February 1606. However, he believed the Cape to be part of New Guinea, from whence he crossed the Arafura Sea.
In 1616, Dutch sea-captain Dirk Hartog sailed too far whilst trying out Henderik Brouwer's recently discovered route from the Cape of Good Hope to Batavia, via the Roaring Forties. Reaching the western coast of Australia, he landed at Cape Inscription on 25 October 1616. His is the first known record of a European visiting Western Australia's shores.
First European to discover Australia was in 1606 by Willem Janszoon.