Red Sea, an inlet of the Indian ocean, extending from the straits of Bab-el-Mandeb, lat. 12° 40' N., nearly N. N. W. to Suez, lat. 29° 57' 30", and separating Arabia on the east from Egypt, Nubia, and Abyssinia on the west. Its length is about 1,400 m., its greatest breadth, near lat. 16°, 200 m., and its total area about 185,000 sq. m. At the straits of Bab-el-Mandeb, by which it is joined to the Indian ocean, it is but 18 m. wide, at Hodeida about 95 m., and at Jiddah about 120 m. At Ras Mohammed, lat. 27° 45', it is divided into two branches by the rocky peninsula of Mt. Sinai or Jebel Musa. The western branch, the gulf of Suez, which is the continuation proper of the Bed sea, is about 180 m. long, and has an average breadth of 20 m. It has the same general course as the main part of the sea, with which it is connected by the strait of Jubal. At its N. extremity the Suez canal connects it with the Mediterranean, from which it is separated by the isthmus of Suez. The eastern branch, the gulf of Akabah, extends N. N. E. from its mouth at the strait of Tiran, about 100 m., and has an average breadth of about 12 m. The Bed sea varies greatly in depth.
In the middle of the gulf of Suez it is from 250 to 300 ft. deep, but shoals gradually to 18 or 20 ft. in the harbor of Suez, where it has been filled up by the sand. The gulf of Akabah varies from 700 to 1,500 ft. in depth. The deepest sounding obtained is in the Bed sea proper, in lat. 22° 30', where the depth is 6,324 ft. In the S. part it is shallower, and below lat. 16° its depth ranges from 250 to 750 ft. A section through the middle of the sea from the straits of Bab-el-Mandeb to Suez represents a series of rounded submarine hills, covered with silt, mud, and sand. The sand, which is blown in from the neighboring deserts, constitutes the only distinctive feature between this ooze and that of the bottom of the Atlantic. Near the shores on both sides the water is generally shallow, and navigation is rendered dangerous by many rocky islands, shoals, and coral reefs. The principal islands are the Farsan group on the Arabian coast, about lat. 17°, and the Dah-lac group on the W. side, in lat. 16°, each consisting of large islands surrounded by many smaller ones connected by reefs. In lat. 15° 40' is Jebel Teir, having an active volcano, the summit of which is more than 1,000 ft. above the sea. Nearly S. of it is the Zebayer group.
Kamaran island, off the coast of Yemen, is claimed by the British. In lat. 14° is Jebel Zugur, and in the straits of Bab-el-Mandeb, commanding the entrance from the Indian ocean, is Perim, a fortified British possession. (See Perim.) At the entrance of the gulf of Akabah is the island of Tiran, dividing it into two channels, of which only the western one, called the strait of Tiran, is navigable for large vessels; and at the mouth of the gulf of Suez are Shadwan island and several smaller ones. - The Red sea occupies the bottom of a longitudinal valley lying between the highlands of Arabia on the east and the mountain range on the west, which borders Abyssinia, Nubia, and Egypt. On the N. side, between the gulf of Suez and the Mediterranean, the country is low and flat, and exhibits indications that a communication once existed between the two seas. The mountains are in sight on both sides of the sea, but a considerable part of each coast is low and flat or covered with undulating hills, the mountain range being in some places 20 or 30 m. from the shore. It is probable that the sea once covered the entire basin, but has been filled up in part by the growth of coral and the accumulation of sand.
The Arabian town of Muza, marked as a seaport in the Periplus of Arrian, is now several miles inland. The coral reefs, which are more extensive than in any other sea of equal size, lie generally in long lines parallel to the shores, and from 500 yards to a mile distant from them. The banks are usually from 4 to 6 ft. below the surface, and the water on their outer edge is very deep, but on the inner side they are sometimes connected with the land. Where they are unconnected with the shore there is generally a channel within them navigable for small vessels and having good anchorage. The native vessels make great use of these inner straits, where the heavy winds of the open sea affect them but little. There is no surf on the reefs, as the porous coral permits the passage of the waves through them. The reefs are more numerous on the E. than on the W. side. The growth of continental coral reefs in the Bed sea in a more northerly latitude than elsewhere is accounted for by the absence of rivers on the coast, and by the high temperature of the water, which is seldom below 80° F. In March and April it is sometimes 84°, and in May 90°. The genera of coral are nearly the same as in the central Pacific, and consist of most of the reef-forming species.
Some of the meandrinas and favias are from 6 to 9 ft. in diameter. The coral is generally white, but often red, and a black variety is found along the Arabian coast for 50 m. N. and S. of Jiddah. Sponges of fine quality are taken in abundance along the E. shore of the gulf of Suez, and pearl oysters are found in various places. As the Bed sea receives but little water from the atmosphere or from the surrounding country, and the sun's rays generally fall on it from a cloudless sky, it may be considered merely a basin for evaporation, which proceeds at the rate of about four fifths of an inch a day, or 23 ft. in a year. From a little more than 39 parts of salt in 1,000 at the straits of Bab-el-Mandeb, the proportion rises in the N. part to 43, a degree of saltness found elsewhere only in inland salt lakes. As the concentration of so much salt through evaporation would tend in time to fill up the sea, it is supposed that the waters most charged with salt flow out through the straits in an undercurrent, while the lighter and less saline waters flow in above it. - The winds are generally pretty constant.
From October to May they blow from S. S. E., being strongest in February; the rest of the year they are from N. N. W., and the strongest in June and July. Sailing vessels find great difficulty in beating up against the wind from May to November, and the pilgrim ships from India are often obliged to put in at Hodeida and forward their passengers to Mecca and Medina by land. The tidal wave enters but a little way into the Red sea, and no ebb and flow of the tide is noticeable at the N. extremity. The currents seem to be governed entirely by the winds. When the S. wind blows the water flows toward the gulf of Suez, and the surface is 2 ft. higher than when the N. wind prevails; and after long continued N. winds the upper part of the gulf of Suez is sometimes fordable. In general the waters are at the same level with those of the Mediterranean. The atmosphere of the Red sea is very oppressive during the hot months. In the latitude of Jiddah the average day temperature from December to March is 76°; from March to the end of May, 87°; during June, 93°; in July, August, and September, 100°; and in October and November, 85°. When the S. wind blows in summer the temperature is frequently 107°, and during the simoom, which blows from N. E. and E. N. E., but generally for a few hours only, it sometimes rises to 132°. - The principal ports of the Red sea are: on the gulf of Suez, Suez and Tor; on the African coast, Kosseir, Suakin, and Massowa; and on the Arabian coast, Yambo, the port of Medina, Jiddah, the port of Mecca, Loheia, Hodeida, and Mocha. There are many other small harbors and inlets, frequented by the Arabs, who carry on most of the local commerce, and who from long experience are acquainted with all the intricacies of the coast navigation.
There are several lighthouses: one on Perim, one on the Daedalus shoal, about 200 m. N. of Jiddah, one at Ras Sharib on the W. side of Jubal strait, and three in the gulf of Suez. There is a submarine telegraph cable from Aden to Suez through the Red sea, which since the completion of the canal has become once more the highway of travel and commerce between the Mediterranean and India. (See Canal, and Suez.) - The Red sea is often referred to in the Hebrew Scriptures under the name of Yam Suph, the sea of weeds, so called, it is supposed, from a small seaweed thrown up by its waters, probably the rytiphlaea pinastroides. The name Red is generally traced directly from the Latin Ru-hrum and Greek , which were applied to this sea in common with the Persian gulf and Indian ocean by Herodotus and other ancient writers. (See ErythrAean Sea.) Its origin has been variously deduced from the redness of the surrounding hills, of the coral reefs, of the seaweed, and of the water from the presence of animalcules, from early Phoenician (Or. red) dwellers on the shores of the Erythraean, and from Edom, "red," the Hebrew and Phoenician name of a country adjoining the gulf of Akabah. Himyar, the name of the founder of the Himyarite kingdom of S. W. Arabia, is supposed also to be derived from the Arabic ahmar, "red." The most interesting historical incident connected with the Red sea is the passage of the Israelites across it in their flight from Egypt. (See Exodus.) By the Red sea in ancient times the trade between India and the countries on the Mediterranean was carried on; and upon this sea and the other inland gulfs and seas of this part of the old world the earliest commercial operations were conducted, and the first experience in navigation was gained. The Egyptians and Phoenicians established this trade with India, and so important was it to the former people, that the Pharaoh whom the Greeks call Sesostris is related to have had upon the Arabian gulf a fleet of 400 long vessels or ships of war, by means of which he protected it and subjugated the people on the borders of the sea who interfered with it.
King Solomon built "a navy of ships in Ezion-geber, which is beside Eloth, on the shore of the Red sea, in the land of Edom." (1 Kings ix. 26.) Ezion-geber was at the head of the gulf of Akabah, and these ships constituted the fleet which went to Ophir. For a long time the Heroöpo-lite gulf or gulf of Suez was the chief avenue of the Egyptian traffic; but the shoaling of the water at the head rendered navigation dangerous, and in the reign of Ptolemy Philadelphus this route was nearly abandoned in favor of that by way of the new port of Berenice, near lat. 24°, which was connected by a well constructed road with Coptos on the Nile, whence boats conveyed the merchandise to Alexandria. Myos-Hormos, about lat. 27° 20', was also an important port under the Ptolemies and the Romans, and according to Strabo 120 ships left it annually for India. After the Mohammedan conquest of Egypt, a large commerce was carried on by the Arabs through the Red sea with India and China. In the middle ages the Genoese and Venetians were largely engaged in this trade, until the discovery by the Portuguese of the route by the cape of Good Hope, when the Red sea lost its commercial importance.
This was in part revived when the English established the overland route to India, via the Cairo and Suez railway; and since the opening of the Suez canal this ancient route has once more assumed its former importance.