1. Lake Baikal Lake Baikal is an ancient, massive lake in the mountainous Russian region of Siberia, north of the Mongolian border. Considered the deepest lake in the world, it’s circled by a network of hiking paths called the Great Baikal Trail. The village of Listvyanka, on its western shoreline, is a popular starting point for summertime wildlife-spotting tours, plus wintertime ice-skating and dog sledding. With 23,615.39 km 3 (5,670 cu mi) of fresh water, it contains more water than all of the North American Great Lakes combined. ... With a maximum depth of 1,642 m (5,387 ft), Baikal is the world's deepest lake . It is among the world's clearest lakes and is the world's oldest lake , at 25–30 million years. Lake Baikal is so deep because it is located in an active continental rift zone. The rift zone is widening at a rate of about 1 inch (2.5 cm) per year. As the rift grows wider, it also gro...