Baku, October 19, AZERTAC Lake Baikal in southern Siberia, Russia, remains covered with ice for almost five months a year. Known as the 'Galapagos of Russia', its age and isolation have produced one of the world's richest and most unusual freshwater faunas, which is of exceptional value to evolutionary science.Every winter as the temperature plummets below zero, the surface of the world’s largest freshwater lake freezes. But ice doesn’t begin to form until the middle of winter, long after the beginning of severe Siberian frosts. When other rivers and lakes froze long before in the year, Baikal still resists ice formation. Lake Baikal is truly interesting. As the world’s deepest and largest freshwater lake by volume, it contains roughly 20% of the world's unfrozen surface fresh water. It is considered among the world's clearest lakes and the world's oldest lake at 25 million years. It is also the seventh-largest lake in the world by surface area. The crescent shaped lake is located in an ancient rift valley, and is home to thousands of species of plants and animals, many of which exist nowhere else in the world.The lake was declared a UNESCO World Heritage Site in 1996.