The Democratic Republic of the Congo (D.R.C.) includes the greater part of the Congo River basin, which covers an area of almost 1 million square kilometers (400,000 sq. mi.). The country's only outlet to the Atlantic Ocean is a narrow strip of land on the north bank of the Congo River.

The vast, low-lying central area is a basin-shaped plateau sloping toward the west and covered by tropical rainforest. This area is surrounded by mountainous terraces in the west, plateaus merging into savannas in the south and southwest, and dense grasslands extending beyond the Congo River in the north. High mountains are found in the extreme eastern region.

D.R.C. lies on the Equator, with one-third of the country to the north and two-thirds to the south. The climate is hot and humid in the river basin and cool and dry in the southern highlands. South of the Equator, the rainy season lasts from October to May and north of the Equator, from April to November. Along the Equator, rainfall is fairly regular throughout the year. During the wet season, thunderstorms often are violent but seldom last more than a few hours. The average rainfall for the entire country is about 107 centimeters (42 in.).