The Gulf of İzmir, formerly known as the Gulf of Smyrna, is a gulf on the Aegean Sea, with its inlet between the Karaburun Peninsula and the mainland area of Foça. It is 64 kilometres (40 mi) in length by 32 kilometres (20 mi) in breadth, with an excellent anchorage. The city of İzmir, an important port city of Turkey, surrounds the end of the gulf.

Smyrna was a Greek city located at a strategic point on the Aegean coast of Anatolia. Due to its advantageous port conditions, its ease of defence, and its good inland connections, Smyrna rose to prominence. Since about 1930, the city's name has been İzmir.