Dakar is the capital and largest city. The main rivers are the S n gal, which forms the northern boundary, and the Saloum, Gambia, and Casamance. Although these rivers are subject to seasonal variations in their flow, all are navigable on their lower courses. Climate Most of Senegal has a transitional climate from the dry desert zone in the north to the moist tropical zone in the south. The northern section of Senegal is part of the Sahel, a transition zone between the Sahara on the north and the wetter regions to the south.
Vegetation here consists largely of savanna grass with scattered clumps of trees and spiny shrubs.
Farther south, in the region of the Gambia River, trees become more common. In the extreme south are mangrove swamps and dense forests of oil palms, mahogany, teak, and bamboo. Wildlife is diverse, but larger mammals, such as the elephants, lions, cheetahs, and antelope, are largely confined to the less populated eastern half of the country. Hippopotamuses and crocodiles are found in the rivers. Among Senegal's numerous varieties of snakes are the cobra and boa constrictor.