An arm of the Arabian Sea, and stretching in a NW. direction between the desolate sandy shores of Turkey in Asia and Africa; is connected with the Gulf of Aden in the SE. by the Strait of Bab-el-Mandeb, and in the NW. divides into the Gulfs of Suez and Akaba, between which lies the Sinai Peninsula; the Suez Canal (q. v .) joins it to the Mediterranean; is 1200 m. long, and averages 180 in breadth; has a mean depth of 375 fathoms (greatest 1200); receives no rivers, and owing to the great evaporation its water is very saline; long coral reefs skirt its shores, and of many islands Jebel Zugur, in the Farisan Archipelago, and Dahlak are the largest; the dangerous Dædalus Reef is marked by a lighthouse; as a seaway between Europe and the East its importance was greatly diminished by the discovery of the Cape route, but since the opening of the Suez Canal it has much more than regained its old position; owes its name probably to the deep red tint of the water often seen among the reefs, due to the presence of microscopic organisms.