Althorpe Islands Conservation Park is a protected area in the Australian state of South Australia occupying the Althorpe Island, Haystack Island and Seal Island in Investigator Strait near the town of Stenhouse Bay.

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.