Heard Island is the top of an active stratovolcano on the Kerguelen Plateau in the southern Indian Ocean, about 4000 km southwest of Western Australia. Part of Australian territory, along with McDonald Island to the west, Heard is one of Australia's two currently active volcanoes.
The volcano is frequently active, and occasional reports of eruptions date back to 1881. Since about 1980, remote sensing mostly via satellites has been able to detect more and frequent activity at the volcano.
The 368 sq km island with its highest point Mawson Peak at 2745 m forms the highest point of Australian territory outside Antarctica.
The uninhabited island was discovered by and named after Captain John Heard in 1853. Its remote location and typically extremely adverse weather and wind conditions make it difficult to access and only few expeditions have reached it. An Australian navy base existed on the island at Atlas Cove on the western side of Big Ben between December 1947 and March 1955.