Adriatic Sea, a large arm of the Mediterranean Sea, extending 450 miles north-westward between Italy and the Balkan Peninsula, and terminated to the south by the strait of Otranto, 45 miles wide. The west coast is comparatively low and has few inlets, and the north is marshy and edged with lagoons. On the other side, the coasts of Illyria, Croatia, Dalmatia, and Albania are steep, rocky, and barren, with many inlets, and begirt with a chain of almost innumerable small rocky islands. The total area of the sea, including islands, is calculated at 52,220 sq. m. - the area of the islands being 1290; the mean depth is 110 fathoms, the greatest depth 565 fathoms. The chief rivers flowing into it are the Adige and the Po, which are continually depositing soil on the coast, so that places once on the shore are now inland. The extreme saltness of the Adriatic is probably owing to the comparatively small quantity of fresh water poured into it by rivers. Venice, Trieste, Fiume, Ancona, Bari, and Brindisi are the chief ports. The fisheries are rich, and industriously worked.