III.

Economy

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.