Investigator Strait is a body of water in South Australia lying between the Yorke Peninsula, on the Australian mainland, and Kangaroo Island. It was named by Matthew Flinders after his ship, HMS Investigator, on his voyage of 1801–1802. It is bordered by the Gulf St Vincent in the northeast.

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 is separated from Kangaroo Island to the south by Investigator Strait.