The first voyage of Cook had completed the general survey of the Australian continent, and fixed a limit to its extension towards the east; but still its coasts remained to be accurately examined, and many parts were still wholly unknown. It was traditionally recollected that the Spanish navigator, Torres, had sailed to the south of New Guinea; but his voyage met with little attention or credit till 1762, when, on the taking of Manilla, a manuscript journal of his voyage was discovered, which gave authenticity to the almost forgotten rumours of his discoveries. Still Cook seems to have doubted the existence of a strait between New Guinea and Terra Australis; and when he sailed between them in 1770, his achievement had the brilliancy of a new discovery.

The Dutch navigators had coasted the northern shores at a very early period, and Tasman is supposed to have completed the survey of that part of the continent; but as the jealous policy of the Dutch government suppressed the publication of these voyages, other nations remained incredulous as to the reality of discoveries which were in some measure concealed from them. The Dutch themselves, it appears, had never solved to their own satisfaction the most important questions respecting the great Australian land, as they still remained ignorant of a great portion of the eastern and western eoasts. They thought it probable that the lands discovered on the north and on the south were separated from each other by a great strait running from east to west. The first voyage of Cook, by establishing the continuity of the eastern coast, overturned this hypothesis.