The origin of the Sea of Marmara is associated with large faults of the Earth’s crust, which divided the continents of Europe, Asia and Africa. The first description of the coast of the sea was carried out in 1845-48 by the captain-lieutenant of the Russian fleet MP P. Manganari. The shores are predominantly mountainous, in the south and east they are highly dissected (the bays of Izmit, Gemlik, etc.). The largest islands are Marmara, Princes, the northern coast has underwater reefs. The small rivers Granic, Susurluk, and others (practically all from the Asian coast) flow into the sea. The sea does not freeze; in winter, the water temperature on the surface is 9 ° C, in summer it is up to 29 ° C. The hydrology of the sea is characterized by the exchange of waters of the Black and Aegean seas through the straits. Salinity on the surface is up to 26, which is much more than in the Black Sea, but significantly less than in the oceans. At the same time, the salinity of the bottom water is noticeably higher - up to 38%, which is comparable to the salinity of the waters of the Mediterranean. The flora and fauna of the Sea of Marmara has a species composition related to the Mediterranean. The coast of the sea is densely populated since ancient times; Istanbul is located in the northeast, near the Bosphorus. On the shore - numerous resorts (Erdek, Moudania, etc.).