the coast is for the most part flat, with occasional low cliffs and bluffs of red sandstone. there is but one deep inlet of the sea – great fish bay (or baía dos tigres). farther north are port alexander, little fish bay and lobito bay, while shallower bays are numerous. lobito bay has water sufficient to allow large ships to unload close inshore. the coastal lowland rises from the sea in a series of low terraces. this region varies in width from about 25 km near benguela to more than 150 km in the cuanza river valley just south of angola's capital, luanda, and is markedly different from angola's highland mass. the atlantic ocean's cold, northwardflowing benguela current substantially reduces precipitation along the coast, making the region relatively arid or nearly so south of benguela (where it forms the northern extension of the namib desert), and quite dry even in its northern reaches. even where, as around luanda, the average annual rainfall may be as much as fifty centimeters, it is not common for the rains to fail. given this pattern of precipitation, the far south is marked by sand dunes, which give way to dry scrub along the middle coast. portions of the northern coastal plain are covered by thick brush.