Two rival maps disagree how big Australia’s southern bight is
The Great Australian Bight opens along the continent’s central-west south coast—an oceanic gulf born when Gondwana split Australia from Antarctica some 50 million years ago. Hydrographers still argue whether it belongs to the Indian or Southern Ocean.
The Dutch navigator François Thijssen sailed its western edge in 1627, and Matthew Flinders charted it accurately in 1802. The International Hydrographic Organization draws a vast area from West Cape Howe to Tasmania’s South West Cape, closed in the east by a line from Cape Otway via King Island to Cape Grim. The Australian Hydrographic Service limits the name to about 1,160 km of coast from Cape Pasley to Cape Carnot, and abroad the gulf usually counts as Indian Ocean while Australia assigns it to the Southern Ocean.
Cape Pasley is an outcrop of the ancient Yilgarn craton; from there the Wylie Scarp runs parallel to the shore behind the Israelite Plain before turning inland at the Head of the Bight. Farther east, the western Eyre Peninsula breaks into aeolianite capes, bays, and islands such as Fowlers Bay, Streaky Bay, and the Nuyts Archipelago. Cliffs rise to about 60 metres, and in winter growing numbers of southern right whales draw watchers.
Behind the coast lies the Nullarbor Plain, a flat limestone seabed lifted during the Miocene and now arid, so little runoff reaches the sea. The shallow shelf waters are therefore nutrient-poor, but seasonal upwelling lifts deep nutrients shoreward and particular currents make the zooplankton unusually diverse. Southern bluefin tuna have long been the favoured catch, alongside earlier whaling and shellfish industries, and researchers stress that much about the ecosystem remains unknown.
Oil and gas exploration began in the late 1960s; BP, Equinor, and Chevron proposed exploration wells from 2017, though BP dropped its plans on 11 October 2016. The Eyre Highway skirts the cliffs between the Head of the Bight and Eucla, Ceduna and Eucla offer access to the water, and the Eyre Bird Observatory studies the coast’s natural history.
Source: Great Australian Bight
