The topography of Egypt is dominated by the Nile. For about 750 miles (1,200 km) of its northward course through the country, the river cuts its way through bare desert, its narrow valley a sharply delineated strip of green, abundantly fecund in contrast to the desolation that surrounds it. From Lake Nasser, the river’s entrance into southern Egypt, to Cairo in the north, the Nile is hemmed into its trenchlike valley by bordering cliffs, but at Cairo these disappear, and the river begins to fan out into its delta. The Nile and the delta form the first of four physiographic regions, the others being the Western Desert (Arabic Al-?a?r?? al-Gharbiyyah), the Eastern Desert (Al-?a?r?? al-Sharqiyyah), and the Sinai Peninsula.
The Nile divides the desert plateau through which it flows into two unequal sections—the Western Desert, between the river and the Libyan frontier, and the Eastern Desert, extending to the Suez Canal, the Gulf of Suez, and the Red Sea. Each of the two has a distinctive character, as does the third and smallest of the Egyptian deserts, the Sinai. The Western Desert (a branch of the Libyan Desert) is arid and without wadis (dry beds of seasonal rivers), while the Eastern Desert is extensively dissected by wadis and fringed by rugged mountains in the east. The desert of central Sinai is open country, broken by isolated hills and scored by wadis.
Egypt is not, as is often believed, an entirely flat country. In addition to the mountains along the Red Sea, mountainous areas occur in the extreme southwest of the Western Desert and in the southern Sinai Peninsula. The high ground in the southwest is associated with the ?Uwayn?t mountain mass, which lies just outside Egyptian territory.
The coastal regions of Egypt, with the exception of the delta, are everywhere hemmed in either by desert or by mountain; they are arid or of very limited fertility. The coastal plain in both the north and east tends to be narrow; it seldom exceeds a width of 30 miles (48 km). With the exception of the cities of Alexandria, Port Said, and Suez and a few small ports and resorts such as Mars? Ma?r?h and Al-?Alamayn (El-Alamein), the coastal regions are sparsely populated and underdeveloped.