The Gulf of Alexandretta, also known as the Gulf of Issus or Gulf of İskenderun (Turkish: İskenderun Körfezi), called Mare Issicum or Issicus Sinus by the Romans, forms the easternmost embayment of the Mediterranean Sea at the southern coast of Turkey near its border with Syria. It is a gulf or inlet of the Levantine Sea, the eastern part of the Mediterranean basin. The gulf bounds parts of the Turkish provinces of Adana and Hatay and the city of İskenderun, formerly known as Alexandretta.
The eastern and southern coasts of the gulf had been shaped by the Nur Mountains (Turkish: Nur Dağları, lit. 'Mountains of Light'). On the northern coastline lies the region of Çukurova (Cilicia).