Aden, Gulf of (äˈdən, āˈ–) [key], western arm of the Arabian Sea, 550 mi (885 km) long, lying between Yemen and Somalia; connected with the Red Sea by the Bab el Mandeb. The gulf is on the great Mediterranean Sea–Indian Ocean trade route. After the 16th cent. Portugal, Turkey, and Great Britain were the chief contenders for control of the gulf, but by the 19th cent. Britain dominated the area. In the late 1960s, British military withdrawal E of Suez led to an increased Soviet naval presence in the gulf area. The importance of the Gulf of Aden declined when the Suez Canal was closed, but it was revitalized when, after being deepened and widened by Egypt, the canal was reopened in 1975 and marine activity increased. The Gulf of Aden is richly supplied with fish, turtles, and lobsters.