Sea or, lies between European and Asiatic Turkey, between 40. 18. and 41. 5. N. Lat., 26. 40. and 30. 5. E. Long. It is 172 miles in length by 55 in breadth. At the east end it terminates in two long and narrow gulfs,—that of Izmid to the N., and that of Mudanich to the S. It communicates with the Black Sea at the N.E. by the Bosphorus or Straits of Constantinople, and with the Archipelago on the S.W. by the Dardanelles. The shores of the Sea of Marmora are beautiful in scenery and well cultivated; but those on the Asiatic side are bolder and more precipitous than those on the European. In some places the depth is very great; at a point 5 miles N. of Marmora Island no soundings have been obtained at 355 fathoms; and it is believed that in the centre the depth is very much greater. It is fed by several streams, of which the most important are the Karasu, Jatiçi, and Chortu from Europe, and the Salataderç, Gweimenshar, Mukhalitch, and Hyla from Asia. The navigation of the sea is safe, and not accompanied with much difficulty; and there are numerous good harbours on the northern shore and under the islands. This sea is not subject to tides; but a current runs through it from the Black Sea to the Mediterranean, varying in strength and swiftness at different seasons. The principal island, Marmora, which has given name to the sea, is celebrated for its marble quarries, from which in ancient times Cyzicus and other neighbouring cities, and in modern times Constantinople, have been supplied with building materials. The island of Marmora is occupied by a mountain range of no great height, and has a very barren appearance, although some wine is here produced. It is thinly inhabited, mostly by Greek Christians; and the town of Marmora, which stands on the S.W. coast, is chiefly built of wood. The island has a circumference of about 45 miles, and was anciently known by the names of Proconnesus or Elephoonenus, on account probably of the deer with which it was then stocked. The other islands are,—Rahi, Liman-Pasha, Papa or Kalolimano, and the group called Prince's Islands or Demonesi. The Sea of Marmora was called by the ancients Propontis, and was believed by them to lie due N. and S., so that the Dardanelles and the Bosphorus were placed on the same meridian.