Baikal (Turkish, Bei-kul, ' rich lake') is, after the Caspian Sea and the Sea of Aral, the largest lake of Asia, with an area of 13,500 sq. m. It is a fresh-water lake, and is situated in the south of Siberia, in the government of Irkutsk, in 51o 20' - 55° 30' N. lat., and 103° - 110° E. long., and somewhat resembles a sickle in shape. Its length is 330 miles, and its breadth 9 1/4 to 40 miles; height above the sea, 1360 feet; mean depth 850 feet, but in some places as much as 4500 feet, more than 3000 feet below sea-level. Its waters are a deep blue, and remarkably clear. Its outlet is by the Lower Angara, a chief tributary of the Yenisei; but the river is inconsiderable in size compared with those which flow into the lake. It has several islands - the largest, Olkhon, 32 miles long. There are numerous hot springs on its shores, and earthquakes are frequent. Formerly the lake - or rather sea - seems to have been much more extensive. The difficult section of the great Siberian railway passing round the south end of the sea was not completed till 1904; the connection being till then carried on by steamers (or across the Baikal ice in winter).

The annual value of its salmon, sturgeon, and other fisheries is estimated at 200,000 roubles. The capture of fresh-water seals is a source of income to the Russian settlers. The surface of the lake is frozen from November to May, but the traffic is carried on over the ice.