Borneo is the third largest island in the world and the main island on the Sunda Shelf. Mount Kinabalu, the highest peak in the Southeast Asian archipelago, is not actually in Indonesia. It rises to 13,455 feet (4,101 metres) in the northeastern corner of the island, in the Malaysian state of Sabah. Otherwise, the island's relief seldom exceeds an elevation of 5,600 feet (1,700 .