Aden,city,SW Yemen, on the Gulf of Aden near the southern entrance to the Red Sea. It is the chief port of Yemen. Aden consists of two peninsulas, Aden and Little Aden, and an intervening stretch of the mainland. Each peninsula has a high volcanic headland (Aden rises to 1,742 ft/531 m, and Little Aden to 1,147 ft/350 m), which is linked to the mainland by a flat, sandy isthmus. The bay between the peninsulas is an excellent harbor. Aden peninsula contains most of the city's population and is divided into a number of districts that were once towns. Wells near Sheikh Othman, on the mainland, supply the city with water. Little Aden peninsula has the city's main industrial district and is the site of a large oil refinery; the manufacture of soap, cigarettes, and salt is also important.