Rising seas drowned the plain that carried people to Tasmania
Bass Strait parts Tasmania from mainland Victoria, linking the Great Australian Bight toward the Tasman Sea. Formed about 8,000 years ago when post-glacial seas flooded the Bassian Plain, it takes its colonial name from surgeon-explorer George Bass (1771–1803).
Bass Strait separates Tasmania from Victoria, apart from a short land border on Boundary Islet, and gives ships the most direct passage between the Great Australian Bight and the Tasman Sea. It is also the sole sea route into Port Phillip Bay, an economically vital harbour. The International Hydrographic Organization draws its western limit from Cape Otway via King Island to Cape Grim and its eastern limit from Gabo Island past Flinders and Cape Barren islands to Eddystone Point. The narrower passage between the Furneaux Islands and Tasmania is called Banks Strait.
Classification is untidy. The IHO's 1953 scheme treats the strait as a subdivision of the Bight, numbered 62-A, while an unapproved 2002 draft put it in the Pacific. The Australian Hydrographic Service leaves it out of the Southern Ocean and groups it with the Tasman Sea.
For most of human history it was dry land. Aboriginal Tasmanians walked south about 40,000 years ago across the Bassian Plain, which joined the coast between Wilsons Promontory and Cape Otway to northern Tasmania between Cape Portland and Cape Grim. When the ice age ended and seas rose, the plain flooded around 8,000 years ago, cutting Tasmania's people off from the mainland. Language evidence points to at least three successive waves of settlement, and people lived on Flinders Island until about 4,000 years ago.
Europeans took a while to notice the gap. Abel Tasman may have sensed it on 5 December 1642, when his ships rounding Eddystone Point were struck by the Roaring Forties blasting through; searching for a southern continent rather than islands, he turned east. James Cook approached in April 1770 but gave up against the wind, unsure whether Van Diemen's Land and New Holland were joined. George Bass and Matthew Flinders settled the matter by sailing right round Van Diemen's Land in the Norfolk in 1798 and 1799, and on Flinders' advice Governor John Hunter named the water after Bass in 1800.
Source: Bass Strait
