Turkey’s marble sea is the Black Sea’s front porch
The Sea of Marmara lies entirely inside Turkey, linking Black Sea to Aegean through the Bosporus and Dardanelles while splitting the country’s European and Asian shores. Greeks called it Propontis—“in front of the sea”—because they crossed it to reach the Black Sea.
The modern name comes from Marmara Island near the southern shore, famous for marble, mármaron in Greek. Legend sets an Argonaut episode here: a storm blew Jason’s crew back to an island they had just left, and in the confused night battle that followed, Jason or Heracles killed King Cyzicus by mistake.
The International Hydrographic Organization closes the sea in the west at the Dardanelles, on a line from Kum Kale to Cape Helles, and in the north-east on a line from Cape Rumili to Cape Anatoli at the Bosporus. The southern coast is deeply cut by the gulfs of İzmit, Gemlik, Bandırma and Erdek.
Surface water averages about 22 parts per thousand of salt, a little more than the Black Sea but only two-thirds of typical ocean water. Near the bottom salinity rises to around 38, close to the Mediterranean, and that dense layer stays put rather than mixing upward. The Susurluk, Biga and Gönen rivers, nearly all flowing from Anatolia because little of Thrace drains south, freshen it further.
Two archipelagos dominate. In the north the Princes’ Islands, including Büyükada, Heybeliada, Burgazada and Kınalıada, belong to the Istanbul conurbation and are served by ferries from both its European and Asian sides. In the south the Marmara Islands of Balıkesir Province, Marmara itself plus Avşa, Paşalimanı, Ekinlik and 17 mostly empty islets such as the prison island of İmralı, are reached from Tekirdağ or Erdek, with summer ferries from central Istanbul bringing tourists to Avşa and Marmara. Koç Adası off Tuzla is privately owned by the Koç industrial family.
Source: Sea of Marmara
