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.

Protected areas of South Australia, consisting of protected areas located within South Australia and its immediate onshore waters and which are managed by South Australian Government agencies. As of 2018, South Australia contained 359 separate protected areas declared under the National Parks and Wildlife Act 1972, the Crown Land Management Act 2009 and the Wilderness Protection Act 1992. Together, they cover a total land area of 211,387.48 km2 (81,617.16 sq mi) or 21.5% of the state's area.