The Althorpe Islands are a group of islands in the Investigator Strait, off the south-western tip of Yorke Peninsula, South Australia. The group includes Althorpe Island and two rocky islets immediately to its west known as The Boobs. These are located 7.7 km south-southwest of Cape Spencer on the mainland. Closer inshore are Seal Island and Haystack Island, which together with Althorpe Island and The Boobs constitute the Althorpe Islands Conservation Park. A management plan for the Althorpe Islands Conservation Park was adopted in 2009. The islands are uninhabited and can only be accessed by sea or by helicopter.