The greatest part of Sudan is a vast plain traversed by the northward-flowing Nile River and its tributaries. Widely separated mountain chains and many hilly areas often reach altitudes of more than 2,000 m (6,500 ft). The northern area is mainly desert, with rock at or near the surface covered by thin soils of low fertility. The western undulating sandy wastes merge into the Red Sea Hills to the east.
The dominating geographic feature is the Nile River, formed near Khartoum by the confluence of the Blue Nile and White Nile rivers. There are natural harbors at Port Sudan (Bur Sudan) and Suakin on the Red Sea.
The highest elevation is at Mount Kinyeti 3187 m (10,456 ft) along the southern border with Uganda.