Bass Strait

Bass Strait separates the island state of Tasmania from the Australian mainland, specifically the coast of Victoria, except for the land border at Boundary Islet. It serves as the most direct water route between the Great Australian Bight and the Tasman Sea, and it is the only maritime passage into the economically important Port Phillip Bay.

The strait formed about 8,000 years ago when sea levels rose at the end of the last glacial period. European colonists named it after English explorer and physician George Bass (1771–1803).

According to the International Hydrographic Organization, the strait’s western limit is the eastern boundary of the Great Australian Bight, running from Cape Otway to King Island and then to Cape Grim on Tasmania’s northwest tip. Its eastern limit is the western boundary of the Tasman Sea, running from Gabo Island to the northeast point of East Sister Island, then along the 148th meridian to Flinders Island, east of the Vansittart Shoals to Cape Barren Island, and from Cape Barren to Eddystone Point in Tasmania.

Some authorities consider the strait part of the Pacific Ocean, as in the never-approved 2002 IHO draft. The current 1953 IHO draft associates it with the Great Australian Bight, designating the Bight as number 62 and Bass Strait as 62-A. The Australian Hydrographic Service does not include it in its expanded definition of the Southern Ocean, instead placing it within the Tasman Sea. The passage between the Furneaux Islands and Tasmania is called Banks Strait, a subdivision of Bass Strait.

Aboriginal Tasmanians first arrived in Tasmania around 40,000 years ago during the last glacial period, crossing a broad prehistoric land bridge known as the Bassian Plain, which connected what is now southern Victoria (from Wilsons Promontory to Cape Otway) to northern Tasmania (from Cape Portland to Cape Grim). When the glacial period ended, rising sea levels flooded the plain, forming Bass Strait about 8,000 years ago and isolating the Tasmanian Aboriginal population from the mainland. Aboriginal people lived on Flinders Island until roughly 4,000 years ago. Based on recorded language groups, there were at least three successive waves of Aboriginal colonisation.

European exploration of the strait may have begun with Captain Abel Tasman in 1642, when he charted Tasmania’s coast. On December 5, following the east coast northward, the land veered northwest at Eddystone Point. Tasman tried to stay with it, but his ships were hit by the Roaring Forties blowing through the strait. Since his mission was to find the Southern Continent, not more islands, he turned east and continued. Captain James Cook approached the strait in HMS Endeavour in April 1770, but after sailing westward against the wind for two hours, he turned back, noting in his journal that he was uncertain whether Van Diemen’s Land and New Holland were one landmass or two.

The strait was named after George Bass after he and Matthew Flinders sailed across it while circumnavigating Van Diemen’s Land (now Tasmania) in the Norfolk in 1798–99. At Flinders’ recommendation, Governor John Hunter of New South Wales named the waterway “Bass’s Straits” in 1800, and it became known as Bass Strait in 1798. The strait’s existence had been suggested in 1797 by the master of the Sydney Cove, who reached Sydney after deliberately grounding his foundering ship and being stranded on Preservation Island. He reported that strong southwesterly swells, tides, and currents indicated the island lay in a channel linking the Pacific and southern Indian Ocean. Governor Hunter wrote to Joseph Banks in August 1797 that a strait seemed certain. When news of the 1798 discovery reached Europe, the French government sent a reconnaissance expedition under Nicolas Baudin, prompting Governor King to dispatch two vessels from Sydney to establish a garrison at Hobart.

Strong currents between the Antarctic-driven southeast Indian Ocean and the Tasman Sea’s Pacific waters create powerful, wild storm waves in the strait. Shipwrecks on the Tasmanian and Victorian coasts number in the hundreds, though stronger metal ships and modern navigation have greatly reduced the danger. Many vessels, including large ones, have disappeared without a trace or left little evidence. Despite myths of piracy, wrecking, and supernatural phenomena similar to the Bermuda Triangle, these disappearances are usually due to treacherous wind and sea conditions and the many semi-submerged rocks and reefs. Despite its difficult waters, the strait provided a safer, less boisterous passage for ships traveling from Europe or India to Sydney in the early 19th century, and it saved 700 nautical miles on the voyage.