Lake Baikal is a rift lake in Russia, located in southernSiberia, between Irkutsk Oblast to the north west and the Buryat Republic to the southeast. Lake Baikal is the largest (by volume) freshwater lake in the world, containing roughly 20% of the world's unfrozen surface fresh water. With a maximum depth of 1,642 m (5,387 ft), Baikal is the world's deepest lake. It is considered among the world's clearest lakes and is considered the world's oldest lake at 25 million years. It is the seventh-largest lake in the world by surface area. With 23,615.39 km3 (5,700 cu mi) of fresh water,it contains more water than all the North American Great Lakes combined.