evidence: The Tanzania mainland is bounded by Uganda, Lake Victoria, and Kenya to the north, by the Indian Ocean to the east, by Mozambique, Lake Nyasa, Malawi, and Zambia to the south and southwest, and by Lake Tanganyika, Burundi, and Rwanda to the west. [...] The East African Rift System runs in two north-south-trending branches through mainland Tanzania, leaving many narrow, deep depressions that are often filled by lakes. One branch, the Western Rift Valley, runs along the western frontier and is marked by Lakes Tanganyika and Rukwa, while the other branch, the Eastern (or Great) Rift Valley, extends through central Tanzania from the Kenyan border in the region of Lakes Eyasi, Manyara, and Natron south to Lake Nyasa at the border with Mozambique. The central plateau, covering more than a third of the country, lies between the two branches. [...] Because of its numerous lakes, approximately 22,800 square miles (59,000 square km) of Tanzania’s territory consists of inland water. Lake Victoria, which ranks as the world’s second largest freshwater lake, is not part of the Rift System. Although Tanzania has no big rivers, it forms the divide from which the three great rivers of the African continent rise—the Nile, the Congo, and the Zambezi, which flow to the Mediterranean Sea, the Atlantic Ocean, and the Indian Ocean, respectively. Separated by the central plateau, the watersheds of these rivers do not meet.