Senegal's largest rivers—the Senegal, Siné, Saloum, Gambia, and Casamance—are sluggish, marsh-lined streams emptying into broad estuaries along the Atlantic Ocean. The Senegal River is the longest at 4,023 kilometers (2,500 miles).
The local climate is tropical with well-defined dry and humid seasons that result from northeast winter winds and southwest summer winds.
Politics in Senegal takes place within the framework of a semi-presidential, democratic republic. The President of Senegal is the head of state and the Prime Minister of Senegal the head of government. Executive power in Senegal is concentrated in the president's hands.