The lake located in the southern part of eastern Siberia within the republic of Buryatia and Irkutsk oblast (province) of Russia. It is the oldest existing freshwater lake on Earth (20–25 million years old), as well as the deepest continental body of water, having a maximum depth of 5,315 feet (1,620 metres). Its area is some 12,200 square miles (31,500 square km), with a length of 395 miles (636 km) and an average width of 30 miles (48 km).