Aden (ˈɑːdɛn ) is a seaport city in Yemen
The Republic of Yemen , commonly known as Yemen , is a country located in the Middle East, occupying the southwestern to southern end of the Arabian Peninsula. It is bordered by Saudi Arabia to the north, the Red Sea to the west, and Oman to the east....

, located by the eastern approach to the Red Sea (the Gulf of Aden
Gulf of Aden
The Gulf of Aden is located in the Arabian Sea between Yemen, on the south coast of the Arabian Peninsula, and Somalia in the Horn of Africa. In the northwest, it connects with the Red Sea through the Bab-el-Mandeb strait, which is about 20 miles wide....

), some 170 kilometres east of Bab-el-Mandeb
The Bab-el-Mandeb meaning "Gate of Grief" in Arabic , is a strait located between Yemen on the Arabian Peninsula, Djibouti and Eritrea, north of Somalia, in the Horn of Africa, and connecting the Red Sea to the Gulf of Aden...

. Its population is approximately 800,000. Aden's ancient, natural harbour lies in the crater of an extinct volcano
2. Bedrock3. Conduit 4. Base5. Sill6. Dike7. Layers of ash emitted by the volcano8. Flank| 9. Layers of lava emitted by the volcano10. Throat11. Parasitic cone12. Lava flow13. Vent14. Crater15...

 which now forms a peninsula
A peninsula is a piece of land that is bordered by water on three sides but connected to mainland. In many Germanic and Celtic languages and also in Baltic, Slavic and Hungarian, peninsulas are called "half-islands"....

, joined to the mainland by a low isthmus
An isthmus is a narrow strip of land connecting two larger land areas usually with waterforms on either side.Canals are often built through isthmuses where they may be particularly advantageous to create a shortcut for marine transportation...

. This harbour, Front Bay, was first used by the ancient Kingdom of Awsan
Kingdom of Awsan
The ancient Kingdom of Awsan in South Arabia , with a capital at Hagar Yahirr in the wadi Markha, to the south of the wadi Bayhan, is now marked by a tell or artificial mound, which is locally named Hagar Asfal. Once it was one of the most important small kingdoms of South Arabia...

 between the 5th and 7th centuries BCE. The modern harbour is on the other side of the peninsula.

Aden consists of a number of distinct sub-centers: Crater
Crater (Yemen)
Crater, also Kraytar, is one of the unofficial names of the oldest districts of the port city of Aden. Its official name is Seera . It is situated in a crater of an ancient volcano which forms the Shamsan Mountains...

, the original port city; Ma'alla, the modern port; Tawahi
Tawahi (Aden)
-History:Tawahi known as "Steamer Point" in the colonial days. It was planned as a modern port by colonial Britain and was part of Aden Settlement.-Population:Its population in 2004 is about 52,984....

, known as "Steamer Point" in colonial days; and the resorts of Gold Mohur.