Aden (Arabic: عدن) is a substantial port on the coast of the Indian Ocean, the most important city of southern Yemen, and former capital of South Yemen. The old town (also known as Crater) is located in the crater of an inactive volcano. Aden is also home to one of the world's largest natural harbours, which has been the economic heart of the city for centuries. Soon after the opening of the Suez canal, the port became the third largest in the world (after those of New York and Liverpool), and it is still one of the major ports in the region.
In the West, the city is best known for a surprise suicide attack that al-Qaeda carried out there on the U.S. warship USS Cole (DDG-67), while she was making a refueling stop. A southern secession movement — a remnant from the civil war — is also based there.