Northwestern branch of the Indian Ocean , covering 3,859,000 sq km/1,489,970 sq mi, with India to the east, Pakistan and Iran to the north, and the Arabian Peninsula and Somalia to the west. It is linked with the Red Sea via the Gulf of Aden, and with the Gulf via the Gulf of Oman. Its mean depth is 2,730 m/8,956 ft. The chief river flowing into the Arabian Sea is the Indus, which is linked with a large submarine canyon in the continental shelf. The sea is rich in fish. Surface currents are driven by the monsoon winds, a northeasterly flow from the Somali coast in summer known as the ‘Monsoon Drift’, with a weaker flow in the opposite direction in winter. The Arabian Sea is divided into two basins, the Somali and Arabian, separated by the Carlsberg ridge. This ridge is seismically active, and divides in the Gulf of Aden, one part entering the Red Sea and the other eventually linking with the Great Rift Valley system in eastern Africa. …