World's Oldest Lake - Lake Baikal

Lake Baikal is 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). It is also the world’s largest freshwater lake by volume, containing about one-fifth of the fresh water on the Earth’s surface, some 5,500 cubic miles (23,000 cubic km). Into Lake Baikal flow more than 330 rivers and streams, the largest of which include the Selenga, Barguzin, Upper (Verkhnyaya) Angara, Chikoy, and Uda.

Baikal lies in a deep structural hollow surrounded by mountains, some of which rise more than 6,600 feet (2,000 metres) above the lake’s surface. The lake hollow is not symmetrical, having steep slopes on the western shores and gentler slopes on the eastern. Baikal contains some 45 islets and islands. The influx of water into the lake is primarily from rivers, chiefly the Selenga. The only outflow is through the Angara River, a tributary of the Yenisey.

Baikal’s climate is much milder than that of the surrounding territory. Winter air temperatures average −6° F (−21° C), and August temperatures average 52° F (11° C). The lake surface freezes in January and thaws in May or June. The water is very clear; from the surface one can see to 130 feet (40 metres). Its salinity is low, and it contains few minerals.

Plant and animal life in the lake is rich and various. There are between 1,500 and 1,800 animal species at different depths, and hundreds of plant species live on or near the surface. There are more than 320 bird species in the Baikal area.