The Seyhan River (formerly written Seihan, Sihun; ancient name: Σάρος, Sarus) is the longest river in Turkey that flows into the Mediterranean Sea. The river is 560 km and flows southwest from its headwaters in the Tahtalı-Mountains (in Sivas and Kayseri provinces) in the Anti-Taurus Mountains to the Mediterranean Sea via a broad delta. Its main tributaries are Zamantı and Göksu, which unite in Aladağ, Adana to form the Seyhan River.