|Location||Fleurieu and Sir Richard Peninsulas, South Australia|
|Primary inflows||River Murray|
|Islands||Granite Island, Pullen Island, Seal Island, Wright Island|
Goolwa, Middleton & Port Elliot
Encounter Bay is a bay in the Australian state of South Australia located on the state's south central coast about 100 kilometres (62 mi) south of the state capital of Adelaide. It was named by Matthew Flinders after his encounter on 8 April 1802 with Nicolas Baudin, the commander of the Baudin expedition of 1800-03. It is the site of both the mouth of the River Murray and the regional city of Victor Harbor. It is one of four 'historic bays' located on the South Australian coast.
There are at least two definitions of the bay's extent. Firstly, an American source states that Newland Head is its westerly extremity while the mouth of the River Murray is the easterly extremity. Secondly, Australian authorities consider the bay's extent consists of all of the sea north of a line running east from the southern tip of Rosetta Head to the Younghusband Peninsula. Encounter Bay is one of four bays on the South Australian coast considered by the Australian government to be a 'historic bay' under the Seas and Submerged Lands Act 1973 and was proclaimed as such in 1987 and again in both 2006 and 2016, with the result that the mouth of the bay is on the territorial seas baseline and the waters within the bay are internal waters as per the definition used in United Nations Convention on the Law of the Sea.
Traditionally the land of the Ramindjeri clan of the Ngarrindjeri people, the bay's coastline is the site for the following settlements: Victor Harbor, Port Elliot, Middleton and Goolwa. The Murray, Inman and Hindmarsh Rivers drain into the bay.
Encounter Bay was named by Matthew Flinders on 8 April 1802 after his encounter with Nicolas Baudin, both of whom were charting the Australian coastline for their respective countries (Britain and France). The encounter between the scientists was peaceful, even though they believed their countries were at war at the time. (Both parties were unaware that the Treaty of Amiens, ceasing hostilities, had been signed on 25 March 1802.)
Shore-based bay whaling stations operated on the coast of Encounter Bay from June 1837 at Police Point, Granite Island and Rosetta Head. The last of these closed down in 1855. They were the most successful and longest lasting whaling stations in South Australia. An attempt was made to re-establish the fishery in 1871-72.
The following protected areas exist within the bay's waters: the Granite Island Recreation Park, the Pullen Island Conservation Park and the West Island Conservation Park, while the bay's waters are within the boundaries of the Encounter Marine Park. The following protected areas adjoin the shores of the bay: the Coorong National Park.