Gulf St Vincent is a large inlet of water on the southern coast of Australia, in the state of South Australia. It is bordered by Yorke Peninsula on its west, the mainland and Fleurieu Peninsula to its east and with its entrance as being a line from Troubridge Pointon Yorke Peninsula to Cape Jervis on Fleurieu Peninsula.

Adelaide, the South Australian capital, lies midway along the gulf's east coast. Other towns located on the gulf, from west to east include Edithburgh, Port Vincent, Ardrossanand Port Wakefield and Normanville. It was named "Gulph of St. Vincent" by Matthew Flinders on 30 March 1802, in honour of Admiral John Jervis (1st Earl of St Vincent).[5]It was later mapped by Nicolas Baudin, who named it as Golphe Josephine, after his meeting with Flinders at Encounter Bay on 8 April 1802. Due to Flinders' lengthy imprisonment on Mauritius during his return to England, the publication of Baudin's mappreceded that of Flinders by three years.

The Adelaide Desalination Plant which is located on Gulf St Vincent's eastern shore in Lonsdale, South Australia, supplies the Adelaide metropolitan area with desalinated water from the gulf. It officially opened in 2013.

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