Heard Island and McDonald Islands

Heard Island and McDonald Islands, subantarctic island groups, together forming an external territory of Australia and lying in the southern Indian Ocean 2,500 miles (4,000 km) southwest of Perth. Volcanic in origin, Heard Island is 27 miles (43 km) long, 13 miles (21 km) wide, and rises to 9,005 feet (2,745 metres) at Mawson Peak on Big Ben Mountain. Much of its surface is covered with snow and ice. It was discovered in 1833 by...