Yemen, officially the Republic of Yemen, is a country in West Asia. Including the Socotra Archipelago, mainland Yemen is located in southern Arabia; bordering Saudi Arabia to the north, Oman to the northeast, the south-eastern part of the Arabian Sea to the east, the Gulf of Aden to the south, and the Red Sea to the west, sharing maritime borders with Djibouti, Eritrea, Somaliland and Somalia across the Horn of Africa. Covering roughly 455,503 square kilometres, with a coastline of approximately 2,000 kilometres, Yemen is the second largest country on the Arabian Peninsula by area, and the largest by population.