The detailed exploration of Australia began from Sydney, the earliest settlement, and was directed along the coast rather than towards the interior, the penetration of which was difficult. George Bass, after a short expedition inland, was accompanied by Matthew Flinders in exploring the coast of New South Wales as far as the George River and Hat Hill towards the end of the eighteenth century; in 1797–98 Bass Strait was found to separate Tasmania from the mainland, and that island was circumnavigated. Bass was subsequently lost in South America; but Flinders extended the work in 1801–03, when, having sailed from England, he worked from King George Sound at the south-west of Australia right round the south, east, and north coasts as far as Arnhem Bay, west of the Gulf of Carpentaria, and would have accomplished more but for the unseaworthiness of his ship. Flinders was not only a competent explorer, but also a man of theories: he took the limestone cliffs of the Great Australian Bight (south coast) for coral reefs, and when he entered Spencer Gulf he thought of a northward strait connecting with the Gulf of Carpentaria, and conceived an Australian archipelago; nor was he wholly disabused until he had definitely located the heads of both gulfs. A number of important inlets, such as Port Phillip, Keppel Bay, and Port Bowen, were thoroughly investigated by him, and he also surveyed the Great Barrier Reef. And the substitution of the name of Australia for New Holland is due to a suggestion of his. His unfinished survey of the western shores was completed by Captain P. P. King in voyages between 1817 and 1822.