Baikal.

Baikal is one of the oldest lakes on the planet, scientists determine its age at 25-30 million years. Most lakes, especially of glacial and ancient origin, live for 10-15 thousand years, and then they are filled with precipitation and disappear from the face of the Earth. There are no signs of aging on Lake Baikal, like many lakes in the world. On the contrary, recent studies have allowed geophysicists to hypothesize that Baikal is an emerging ocean. This is confirmed by the fact that its shores diverge at a rate of up to 2 cm per year, just as the continents of Africa and South America diverge.Among the lakes of the globe, Lake Baikal ranks first in depth (1637 m). On Earth, only 6 lakes have a depth of more than 500 m .Baikal is the largest freshwater storage on the planet (23 thousand cubic km), which exceeds the volume of water contained in the five Great Lakes of North America - Superior, Michigan, Huron, Erie, Ontario combined, or 2 times more than in Lake Tanganyika. About 20% of the world's freshwater reserves of the planet are concentrated in the Baikal basin (excluding glaciers, snowfields and ice, where the water is in a solid state).