Caspian Sea, an inland sea or great salt lake, the largest in the world, on the boundary between Europe and Asia, extending from 36° 40' to 47° 20' N. lat., and 46° 50' to 55° 10' E. long. Its length from north to south is 680 miles, and its breadth varies between 130 and 270 miles. Its total area is estimated at 170,000 sq. m. It has no tides, but navigation is dangerous because of violent storms. Its level differs much at different seasons, owing to evaporation and the variable amount of water brought by its tributaries. It is very shallow in the north - only 14 feet at a distance of 10 miles, and 72 feet at a distance of 130 miles from the mouth of the Volga. In its middle it is intersected by a submarine ridge. The greatest depth found in the northern basin is 2526 feet, and in the southern (close by the southern shore), 3006. The Caspian receives the waters of the Volga, Ural, Emba, Terek, Kura, and Atrek. The water is salt, but much less so than that of the ocean. The northern parts are covered with ice during winter. Fish abounds, and very valuable sturgeon and salmon fisheries are carried on. A canal uniting the upper tributaries of the Volga with those of Lake Ladoga and the Duna connects the Caspian with the Baltic. The sea is now surrounded on three sides by Russian territory, the southern shore still remaining Persian. The Russians have a fleet stationed upon it, and lines of steamers, for which the petroleum of Baku forms an economical fuel. The chief Russian towns on its shores are Astrakhan, Derbend, Baku, and Krasnovodsk, from near which a railway runs by Askabad towards Merv, and thence by Bokhara to Samarkand, with an extension to Tashkand in Turkestan.