An inland sea, partly in Europe and partly in Asia, the largest in the world, being 600 m. from N. to S. and from 270 to 130 m. in breadth, with the Caucasus Mts. on the W. and the Elburz on the S., is the fragment of a larger sea which extended to the Arctic Ocean; shallow in the N., deep in the S.; the waters, which are not so salt as the ocean, abound in fish, especially salmon and sturgeon.