Black Sea, inland sea, c. 159,600 sq mi (413,360 sq km), between South-Eastern Europe and Asia, connected with the Mediterranean Sea by the Bosporus, the Sea of Marmara, and the Dardanelles.
Black Sea is c. 750 mi (1,210 km) from east to west, up to 350 mi (560 km) wide, and has a maximum depth of 7,364 ft (2,245 m). Its largest arm is the Sea of Azov, which joins it through the Kerch Strait. The Black Sea is enclosed by Ukraine on the north, Russia on the north-east, Georgia on the east, Turkey on the south, and Bulgaria and Romania on the west.
The Black Sea was once part of a larger body that included the Caspian and Aral seas. In the Tertiary period, it was separated from the Caspian Sea and was linked to the Mediterranean Sea. Growing evidence suggests that more recently, about 7,600 years ago, at the end of a long dry period, it was flooded suddenly when the Mediterranean, having again become separate, broke through at the Bosporus, an event that may have scattered farmers from its shores into Europe and Asia.
The Dnepr, Southern Buh, Dnestr, and Danube rivers are its principal feeders; the Don and Kuban rivers flow into the Sea of Azov . The rivers flowing into the northern part of the Black Sea carry much silt and form deltas, sandbars, and lagoons along the generally low and sandy northern coast. The southern coast is steep and rocky.
The Black Sea has two layers of water of different densities. The heavily saline bottom layer has little movement and contains hydrogen sulphide; it has no marine life. The top layer, much less saline and richer in fish, flows in a counter-clockwise direction around the sea. There is little tidal action.
Pollution in the Black Sea has spurred surrounding nations to co-operate in instituting environmental safeguards. The sea is subject to severe winter storms, and waterspouts are common in summer.
Ice-free, it was the chief shipping outlet of the USSR; Odessa and Sevastopol in Ukraine and Novorossiysk in Russia are still major ports. Other important ports are Constanta in Romania; Varna and Burgas in Bulgaria; and Trabzon, Samsun, and Zonguldak in Turkey.
The Black Sea region, especially in the Southern Crimea and Western Caucasus, is a popular resort area.
The Pontus Euxinus [hospitable sea] of the ancients, the Black Sea was navigated and its shores colonised by the Greeks between the 8th - 6th centuries BC and later by the Romans between 3rd - 1st centuris BC. Its importance increased with the founding of Constantinople in 330 AD. In the 13th century the Genoese established colonies on the Black Sea, and from the 15th to the 18th century it was a Turkish "lake".
The rise of Russia led to protracted dispute with the Ottoman Empire over control and use of the Bosporus and Dardanelles. In 1783, Russia annexed the Tatar Khanate of Crimea, which blocked its access to the sea, but the Treaty of Paris, which ended the Crimean War of 1856, frustrated Russia's expansionist ambitions, and Russia and its successor, the Soviet Union, retained limited influence in the region.
In 1992, after the breakup of the Soviet Union, the Black Sea Economic Co-operation Zone was established among the nations surrounding the sea.