Lake Baikal is the deepest and, possibly, the most ancient lake in the world; it is about 25 million years old. It holds almost a quarter of the world's supply of fresh water, and the water is extremely pure and clear. A white disk 30 cm in diameter can be seen through the Baikal water even at a depth of 40 meters.
The lake is located at an elevation of almost 500 m above sea level; it is 636 km long and from from 20 to 80 km wide. Lake Baikal and its shores are home to 1,850 species of animals and 850 species of plants, many of which can only be found there. The most famous Baikal fish are the sturgeon, grayling, cisco, and live-bearing oilfish. However, the most valuable of them all is the omul, revered for its exquisite, tender taste.
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The Circum-Baikal Railway. Part of video comes from youtube Thanks to the author.