At , Puncak Jaya is Indonesia's highest peak, and Lake Toba in Sumatra is the largest lake, with an area of 1,145 km2 (442 sq mi). Indonesia's largest rivers are in Kalimantan and New Guinea and include Kapuas, Barito, Mamberamo, Sepik and Mahakam. They serve as communication and transport links between the island's river settlements.