Investigator Strait is a body of water in

South Australia South Australia (commonly abbreviated as SA) is a States and territories of Australia, state in the southern central part of Australia. With a total land area of , it is the fourth-largest of Australia's states and territories by area, which in ...

lying between the

Yorke Peninsula The Yorke Peninsula, known as Guuranda by the original inhabitants, the Narungga people, is a peninsula located northwest and west of Adelaide in South Australia, between Spencer Gulf on the west and Gulf St Vincent on the east. The peninsula ...

, on the

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

n mainland, and

Kangaroo Island Kangaroo Island (, ) is Australia's third-largest island, after Tasmania and Melville Island, Northern Territory, Melville Island. It lies in the state of South Australia, southwest of Adelaide. Its closest point to the mainland is Snapper Poi ...

. It was named by

Matthew Flinders Captain (Royal Navy), Captain Matthew Flinders (16 March 1774 – 19 July 1814) was a British Royal Navy officer, navigator and cartographer who led the first littoral zone, inshore circumnavigate, circumnavigation of mainland Australia, then ...

after his ship, HMS ''Investigator'', on his voyage of 1801–1802. It is bordered by the

Gulf St Vincent Gulf St Vincent, sometimes referred to as St Vincent Gulf, St Vincent's Gulf or Gulf of St Vincent, is the eastern of two large inlets of water on the southern coast of Australia, in the state of South Australia, the other being the larger Sp ...

in the northeast.

Discovery and exploration

It was named Investigator’s Strait by Flinders on Monday 29 March 1802.

Extent

Investigator Strait is bounded by Yorke Peninsula to its north and by Kangaroo Island to its south. Flinders identified its boundaries with the following adjoining bodies of water -

and

Backstairs Passage The Backstairs Passage is a strait in South Australia lying between Fleurieu Peninsula on the Australian mainland and Dudley Peninsula on the eastern end of Kangaroo Island. The western edge of the passage is a line from Cape Jervis (headland), ...

. The Strait’s boundary with

is the line from Troubridge Point on Yorke Peninsula to Cape Jervis on Fleurieu Peninsula. Its boundary with

is the line from Cape Jervis on

Fleurieu Peninsula The Fleurieu Peninsula ( ; locally mainly ) is a peninsula in the Australian state of South Australia located south of the state capital of Adelaide city centre, Adelaide. History Before British colonisation of South Australia, the western s ...

to Kangaroo Head (west of Penneshaw) on Kangaroo Island. Flinders noted that Backstairs Passage is a body of water separate to Investigator Strait. The boundary between the strait and Nepean Bay on the north-east coast of Kangaroo Island is a line between Point Marsden and Kangaroo Head. The Strait’s western boundary by definition is the line from Cape Spencer on Yorke Peninsula to Cape Borda on Kangaroo Island.

Protected areas

A number of

protected areas Protected areas or conservation areas are locations which receive protection because of their recognized natural or cultural values. Protected areas are those areas in which human presence or the exploitation of natural resources (e.g. firewoo ...

are located both within and adjoining the Strait’s extent.

Aquatic reserves

* Troubridge Hill west of Troubridge Point on the south coast of Yorke Peninsula.

Marine parks

* Southern Spencer Gulf Marine Park - the west end of the strait including the coasts of both Yorke Peninsula and Kangaroo Island. * Lower Yorke Peninsula Marine Park - east end of the strait adjoining the south coast of Yorke Peninsula. * Western Kangaroo Island Marine Park - west end of the strait adjoining the north coast of Kangaroo Island. * Encounter Marine Park covers the east end of the strait including its boundaries with Nepean Bay and Backstairs Passage.

National parks and other reserves

The following reserves are located on the south coast of Yorke Peninsula (from west to east): * Innes National Park (includes Chinamans Hat Island) * Point Davenport Conservation Park The following reserves are located on the north coast of Kangaroo Island (from west to east): *

Flinders Chase National Park Flinders Chase National Park (formerly Flinders Chase) is a protected area in the Australian state of South Australia located at the west end of Kangaroo Island about west-south west of the state capital of Adelaide and west of the municipal ...

* Cape Torrens Wilderness Protection Area * Western River Wilderness Protection Area The following reserve is located on Althorpe Islands, Haystack Island and Seal Island at the north-west end of the strait: * Althorpe Islands Conservation Park