"It is more than 25 million years old, a thousand times older than any other lake. At over a mile, it is the deepest lake in the world. If you emptied it, it would take every river in the world flowing into it a year to fill. It contains more water than the five US great lakes combined.
To the shamans and indigenous Mongolian Buryat people, it is one of the most sacred places on earth. With 1,500 species of flora and fauna found nowhere else, including the mysterious nerpa, the only freshwater-lake seal, it has been dubbed the "Galapagos of Russia". But, he said, looking solemn, there are problems…"
The rest of the Guardian article sadly details some of the environmental threats to the lake's health.
Photograph: Olivier Renck/Getty