Black Sea

Black Sea (ancient Pontus Euxinus), inland sea, lying between south-eastern Europe and Asia Minor. It is connected with the Mediterranean (in the Aegean Sea) by the Bosporus, the Sea of Marmara, and the Dardanelles. Romania, Bulgaria, and the European portion of Turkey bound it on the west. The northern and eastern shores are bordered by Ukraine, Russia, and Georgia; the entire southern shore is Turkish territory.

The Black Sea has a length of about 1,200 km (750 mi) from east to west, a maximum width of 610 km (380 mi), and an area (excluding its northern arm, the Sea of Azov) of about 436,400 sq km (168,500 sq mi). The Crimea projects into the Black Sea from the north, forming the shallow Sea of Azov on the east and the Karkinitskiy Gulf on the west. The former is almost entirely cut off from the Black Sea. The sea receives the drainage of a large part of central and eastern Europe through the Dnepr, Dnestr, Southern Bug, and Danube rivers. It also receives waters from a considerable section of eastern European Russia, through the River Don (which flows into the Sea of Azov) and from the western Caucasus region through the Kuban (which also flows into the Sea of Azov), as well as a number of smaller rivers. The Black Sea drains northern Asia Minor through the Çoruh (Chorokhi), Yeşil, Kızıl, and Sakarya rivers. The floor of its single central basin lies about 1,830 m (6,000 ft) below the surface, and the greatest depth exceeds 2,135 m (7,000 ft). Severe storms occur frequently on the sea, particularly during the winter season. The prevailing winter winds are from the north.

Only the top 140 m (459 ft) of the Black Sea are oxygenated, which supports an abundant stock of valuable sturgeon and other fish; the lower levels are almost lifeless because of a high concentration of hydrogen sulphide. As an outlet for the products of Ukraine and adjoining republics, it is of special importance in regional commerce. The principal ports are Odessa, Kherson, and Sevastopol in Ukraine; Poti and Batumi in Georgia; Novorossiysk in Russia; Constanţa in Romania; Burgas and Varna in Bulgaria; and Ereğli, Samsun, Sinop, and Trabzon in Turkey. Summers along the sea can be hot, and many countries have developed resort areas on the coasts.

Navigation in the Black Sea began early. Many of the colonial and commercial activities of ancient Greece and Rome, and in later times of the Byzantine Empire, centred on it. However, recent archaeological studies show evidence of even earlier human presence in the area. It appears that during the Palaeolithic or Mesolithic periods (see Stone Age) people inhabited an area approximately 20 km (12 mi) north of the present Turkish coast, which is 95 m (312 ft) below the current surface of the sea. This discovery lends weight to the theory that the Black Sea was once a freshwater lake, with a much smaller surface area, but was flooded by the Mediterranean Sea about 7,600 years ago, when a change in sea level occurred.

For almost three centuries after 1453, when the Ottoman Turks captured Constantinople, the capital and last stronghold of the Byzantine Empire, the sea was virtually closed to foreign commerce. The Russian Empire began to challenge Turkish supremacy in the Black Sea early in the 18th century. By the terms of the Treaty of Paris of 1856, which ended the Crimean War, the sea was opened to the commerce of all nations and was neutralized. In 1870 Alexander II, emperor of Russia, repudiated the neutralization section of the Treaty of Paris and placed a naval force in the Black Sea. A conference of European powers, held in 1871, sanctioned this action, but reaffirmed the right of the Turkish sultan to close the Dardanelles and the Bosporus to war vessels. Following the defeat of Turkey in the Russo-Turkish War of 1877-1878, the Russians gained important rights for their Black Sea commerce. During World War I the Russian fleet in the Black Sea was active against Turkey.