Ras Siyyan or Ras Siyan ( Arabic: رأس سيان) is a peninsula in the Obock Region of Djibouti, on the Bab-el-Mandeb strait (between the Red Sea and the Gulf of Aden), about 20 km southwest of Perim Island.
The peninsula consists of a reddish volcanic hill about 1.2 by 0.5 km and 138 m high, [1] connected towards to the mainland by a low sandy strip that stretches south by about 5 km while widening from 500 to 800 m. [2] The Ras Siyyan volcano is currently inactive but young, having erupted through a 21,000-year-old coral reef formation. [3]
To the west of Ras Siyyan there is a shallow marshy bay or lagoon, about 2.5 km wide, protected on the north side by shallow coral banks. The bay is fringed with patches of mangrove bushes ( Avicennia marina), in spite of the little input of freshwater. Abundant sea grasses (chiefly Halodule and Thalassia species) form large beds in the bay, and Sharks breed there in October. [3] An isolated white rock, Rocher Siyyan, lies in the bay about 800 m southwest of the volcanic hill.
The hill of Ras Siyyan is sometimes considered the seventh of the Seven Brothers (Sawabi) islands; the other six lie from about 4.5 km to 14.5 km to the east.