Koszalin (kôshäˈlēn) [key], Ger. Köslin, city (1994 est. pop. 110,200), Zachodniopomorskie prov., NW Poland, near the Baltic Sea. Its economy depends on farm products from the surrounding fields, various light industries, and timber milling. It was founded in 1188, prospered from the 14th to the 16th cent., but suffered greatly in the Thirty Years War. There is a 14th-century Gothic cathedral in Koszalin. The city was transferred from Germany to Poland by the Potsdam Conference (1945).