The Russians call Lake Baikal »Siberia’s Blue Eye«, »Siberia’s pearl« or even »A part of the Russian soul«. Lake Baikal is the world’s deepest lake (1637 m), and with a length of 636 km the banana shaped lake has 2000 km of coast line and a total area larger than Belgium. Its volume has been calculated to 23.000 cubic kilometres corresponding to one fifth of all fresh water on earth. It is said that if the world’s water supply stopped tomorrow, Lake Baikal would be able to supply all people on earth with drinking water for the next 40 years. More than 330 rivers flow in to the lake, while only Angara River flows out of the lake. Lake Baikal is famous for having some of the world’s purest and clearest water; in quiet weather it’s possible to see down to 40 metres below the surface. One significant explanation for this is a microscopic crustacean (epishuren) which functions as a filter by excreting 250.000 tons of calcium every year. also In addition, underwater forests of green freshwater fungi and about 258 different shrimp species help to clean the water.