Lake Tanganyika, east central Africa, in the Rift Valley, bordered on the north by Burundi, on the east by Tanzania, on the south by Zambia, and on the west by the Democratic Republic of the Congo. The lake is 680 km (420 mi) long and about 72 km (45 mi) wide at the widest point and covers about 32,900 sq km (12,700 sq mi). The greatest depth is 1,436 m (4,710 ft), making it the second deepest freshwater lake in the world after Lake Baikal. The only outlet is the Lukuga River, which flows into the River Congo. The lake is noted for its many varieties of fish; crocodiles and hippopotamuses are found on the shores, and the surrounding area is very fertile. The lake was first seen by Europeans in 1858, when the British explorers John Speke and Sir Richard Burton arrived here.