The Territory of Heard Island and McDonald Islands (HIMI) is an Australian external territory comprising a volcanic group of mostly barren Antarctic islands, about two-thirds of the way from Madagascar to Antarctica. The group's overall land area is 372 km (144 sq mi) and it has 101.9 km (63 mi) of coastline. Discovered in the mid-19th century, the islands lie on the Kerguelen Plateau in the southern Indian Ocean and have been an Australian territory since 1947.
Heard Island and McDonald Islands contain Australia's only two active volcanoes. The summit of one, Mawson Peak, is higher than any mountain in all other Australian states, territories or claimed territories, except Dome Argus, Mount McClintock and Mount Menzies in the Australian Antarctic Territory. This Antarctic territory is a land claim unrecognised by most other countries, meaning that Mawson Peak is the highest mountain with undisputed Australian sovereignty.
