Which lake is called the “Blue Eye of Siberia”?

Just north of the Mongolian border, in the South-Central Siberian region of Russia, lies a blue, crescent-shaped lake that is thought to be the oldest, deepest, and largest freshwater lake (by volume) in the world. Baikal is a sacred place for those who live in the region, earning it the nickname “Blue Eye of Siberia.” Other nicknames include “the Sacred Sea”, or “the Diamond of the Planet”.

Lake Baikal holds about 5,521 cubic miles (23,013 km3) of fresh water. That amount is approximately equal to all five of the North American Great Lakes combined, according to Geology.com. That’s about 20% of all the fresh water in the world, in just one lake! The lake has an estimated maximum depth of 5,354 feet (1,632 meters), with the lowest point being more than 4,000 feet (1,219 m) below sea level, according to Smithsonian magazine.

Not only is the lake larger and deeper than all others, but the water itself is unique. The lake water is clean, clear, and fresh, and contains very few mineral salts, making it much like distilled water. It also contains a lot of oxygen, even in the depths, which also makes it very unusual..

According to UNESCO, which declared the lake a World Heritage site in 1996, Lake Baikal is the "Galapagos of Russia" due to it biodiversity. About 80 percent of the more than 3,700 species found in the area are endemic (found nowhere else on Earth). Probably the best known of these is the nerpa, the only exclusively freshwater seal on the planet (shown above).