Perim ( [Barīm]), also called Mayyun in Arabic, is a volcanic island in the Strait of Mandeb at the south entrance into the Red Sea, off the south-west coast of Yemen and belonging to Yemen. It administratively belongs to Dhubab District or Bab al-Mandab District, Taiz Governorate. The island of Perim divides the strait of Mandeb into two channels. The island, as a dependency of Aden, was a part of the British Empire between 1857 and 1967. Name In ancient time, it was called "the island of Diodorus" (, ). It is mentioned by Pliny the Elder, by the author of the Periplus of the Erythraean Sea and in Ptolemy's Geography. Perim possibly derives from the Arab term Barim (chain) associated with the history of the Straits and one of its Arab names, the other Arab name being Mayyun. The Portuguese called it Majun or Meho (from Mayyun), although Albuquerque had solemnly named the island Vera Cruz in 1513. On many British and French maps of the 17th and 18th century the island is called Babelmandel, as the Straits are. Some early 19th century navigation guides still call it the island of Bab-el-Mandeb although they may mention that it is also called Perim. By the time the British permanently occupied the island in 1857, the name Perim had come into general usage. Geology Perim island is an eroded fragment of the southwest flank of a late Miocene volcano whose center was on the southwesternmost tip of Arabia. The volcano is the westernmost of the east–west line of six central vent volcanoes (the Aden line) that extends 200 km (125 mi) along the coast of Arabia from Perim to Aden. It is believed that the volcanism is related to an eastward-propagating rift produced before the most recent stage of sea-floor spreading in the Gulf of Aden. Geography Perim is crab-shaped, long and wide. It has a surface area of and rises to an altitude of . Perim encloses a deep and comparatively large natural harbour on the southwestern coast. The fishing village of Mayyun is located at the bottom of the bay. The island divides the wide Bab-el-Mandeb into two: the Large Strait, with an average width of , and the Small Strait, varying from in width. The Large Strait is generally deep water varying from about or more in the middle channel to about close to the coastal reefs. The