Lake Baikal, Russian Ozero Baykal, Lake, southern Siberia, Russia, in Asia. With a length of 395 mi (636 km) long and an area of some 12,200 sq mi (31,500 sq km), it is the largest freshwater basin in Eurasia. It is also the deepest continental body of water on Earth (5,315 ft [1,620 m]), containing one-fifth of the fresh water on Earth’s surface.