Lake Baykal
Baykal (or Baikal), Lake, a lake in Russia, situated in mountainous south-central Siberia near the Mongolian border. Lake Baykal has an area of about 12,200 square miles (31,500 km2). It holds a fifth of the world's freshwater and by volume is the largest lake in the world. The lake extends in a long, narrow arc for about 400 miles (640 km), and has a width of up to 50 miles (80 km). Steep mountains rim the shore in many places, their slopes dropping sharply to the lake's surface. Olkhon Island, near the center of the lake, is the largest of Baykal's 27 islands. Near this island is the lake's deepest point, 5,371 feet (1,637 m)—the greatest depth of any lake in the world.
Of the many streams flowing into Lake Baykal from the surrounding highlands, the largest is the Selenga, which originates in Mongolia. Draining the lake is the Angara River, part of the Yenisey River system. The lake supports a wide variety of life. More than 1,000 species are found nowhere else, including Baykal seals. Pollutants from factories in cities located near the lake's southern shores are a growing threat to the lake.