Saint Helena has a rugged, volcanic terrain, with small scattered plateaus and plains, with the largest area of level ground on the island being Prosperous Bay Plain in the eastern arid area. The other islands of the group have a volcanic origin. The highest point on the island is Diana's Peak at 818 metres (2,684 ft), though Queen Mary's Peak on Tristan da Cunha is the highest in the British territory at 2,062 m.