RED SEA, an Inlet of the Indian detain, which extends from the strait of Babel-Mandeb, in 12' 40' N. lat., in a north by west direction, to 30° N. 1st. It lies between sr 20' and 43' 30' E. long., and is little short of 1400 miles long. From the strait of Babel-3iandeb, which is only 16 miles wide, the Red Sea gradually increases In breadth ; at the distance of 160 miles from the strait it is ISO miles across : this breadth may be considered as the average width from Ras Eesah or the island of Camaran to Jiddah, a distance of nearly 500 milers. Off Jiddah it is not much more than 120 miles wide ; and this width continues to Ras Mohammed, south of 28' N. lat., where the sea divides into two arms; this interval considerably exceeds 500 miles in length. Of the two arms, into which the Red Sea branches off at Ras Mohammed, the eastern is called Bahr•el Akaba, and the western Bahr•el-Suez, or Kolsum. Between these two gulfs is the mountain region of Mount Sinai, or Jibbel Mesa (Mount of Moses). The Bahr-el Akaba branches off in north-eastern direction, and extends more than 100 miles, with an average width of less than 15 miles. Near its entrance is the island of Tiran, which is S00 feet above the level of the sea, and between it and the con tinent are two straits, of which only the western, called the strait of Tiran, is navigable for large vessels. The entrance of the Bahr-el Suez is called the strait of Jubal, or Jublah, and is about 15 miles across. The gulf itself runs in a north by west direction to its extremity at the town of Suez, a distance exceeding 180 miles ; its average width is 20 miles. The surface of the Red Sea is about 180,000 square milee.
The Red Sea is of great depth. The shallowest part is the Gulf of Suez, which in the middle, towards the Strait of Jublah, is from 40 to 50 fathoms deep • farther north its depth decreases to 30 fathoms; and approaching the harbour of Suez, it shoals to 20 fathoms, and by degrees to 3 fathoms, which is the depth of the harbour itself. The Gulf of Akaba varies in its middle part between 100 and 200 fathoms. The main body of the sea is still deeper, and in most parts a bottom cannot be found at the depth of 100 fathoms; in some places it is 230 fathoms deep. Towards the southern extremity, south of 16° N. let., it grows much shallower, the depth in general not exceeding 40 or 50 fathoms.
The sea generally shoals near the shores; but the navigation is rendered difficult by islands, banks, and the prevailing winds. Small
rocky islands are tolerably numerous, especially along the eastern shores, but as they usually contain small harbours they would be rather adeantsgeous were it not for the adjacent reefs. The islands are generally isolated, except between 15° and N. lat., where the group of the Farsan Islands occurs along the eastern shore, and on the western that of the Dhalak Islands, each of which consists of a larger island and a great number of smaller islands, between which there are numerous reefs. South of these groups there are some islands dispersed in the middle of the sea, as Jibbel Teer, the Zebayer Islands (Jezayer es Seba, or the Seven Islands), and others. Two of these islands are volcanic, and on Jibbel Teer there is an active volcano, 900 feet above the sea.
The Red Sea is the most northern portion of the ocean in which coral reefs occur, and they are more numerous than in any other part of the sea of equal extent They almost always extend in a tolerably straight line, parallel to the coast; the interior is filled up, eo that they never contain a lagoon, as is almost Invariably the case with those In the Pacific. These cord-reefs are frequently united with the adjacent continents, and render the shores almost inaccessible, as the water near them is very deep, and the reefs themselves have only from 3 to 6 feet water, which gradually shoals on approaching the beach, so that even boats are stopped at the distance of a quarter of a mile from the dry land. The reefs which are unconnected with the shores are still more numerous, and frequently several miles from them. Their edges towards the open sea are very steep, and the sea iteelf is of great depth. But the edge which is opposite the main. land has usually a gradual and gentle slope, and affords good anchorage to vessels. The sea between this inner edge and the mainland is generally not very deep, and the small Tanis of the country navigate these straits in preference to the open sea, as the water is leas agitated by the winds, and they are always In the neighbourhood of some place which oilers anchorage in case a gale should rise. The winds, which commonly are very strong hi the open sea, can hardly be said to extend to thee* straits, so that small vessels can take advantage of the sea and land breezes, which set in at certain hours of the day during the greatest put of the year. These advantages however are lost by the necessity of putting into some harbour during the night.