Located in western Cilicia, the Göksu (Turkish for "Blue Water", also Güksu Nehri; Coxon, Kalykadnos, Saleph) is a river in southern Turkey that flows through the provinces of Konya, Karaman and Mersin. Its ancient Greek name was Καλύκαδνος (Kalykadnos), Latinized to Calycadnus.
The river is 260 kilometers long. The upper reaches are also called Gökçay (“Blue River”). The most important tributary is the Ermenek Çayı (sometimes referred to as the second source river). Both rivers originate in the Geyik-Dağları ("Deer Mountains") in the Taurus Mountains between Gündoğmuş (Antalya Province, about 50 km north of Alanya) and Hadım (Konya Province). They unite south of Mut to form the (actual) Göksu, which later flows into the Mediterranean Sea between Taşucu and Silifke.
Source: Wikipedia