Lake Baikal in southern Siberia, Russia, is the deepest lake in the world, reaching a maximum depth of 1,642 meters (5,387 feet). Its surface sits about 455 meters above sea level, so its floor lies roughly 1,187 meters below sea level.
Because it is so deep, Baikal is also the largest freshwater lake by volume, holding about 23,600 cubic kilometers of water, more than all of North America’s Great Lakes combined. At an estimated 25 to 30 million years old, it is also considered the world’s oldest lake.
Source: Wikipedia, Lake Baikal