Mersin (mĕrsĭnˈ) [key], formerly Içel ēchĕlˈ, city (1990 pop. 420,750), capital of Içel prov., S Turkey, on the Mediterranean Sea. A rail terminus and modern seaport, it exports cotton, petroleum products, chrome, copper, and agricultural produce. Excavations at Mersin in the 1930s showed that the site was occupied in early Neolithic times (c.3600 B.C.).