Congo River

The Congo is the second-longest river in Africa after the Nile. Encyclopaedia Britannica traces its remotest source to the Chambeshi River in northeastern Zambia; the Lualaba is another major upper branch and carries the greatest volume of water. It follows a broad arc northwest, west and southwest before reaching the Atlantic at the Democratic Republic of the Congo's coast. Its drainage basin extends across much of the Democratic Republic of the Congo and parts of several neighbouring Central African countries. The river's length is usually given as about 4,700 kilometres when the distant headwaters are included.

The Congo is fed by a branching network of rivers and receives water from a large equatorial region. Its flow is substantial, but the main channel is not uniformly navigable: rapids and cataracts divide stretches that can be travelled by boat. In the lower course, a series of cataracts, including Inga Falls, obstructs through-navigation between the Atlantic port of Matadi and Malebo Pool. These changes in slope and channel form are part of why a river with such a large flow can be both a major transport route and a system of separated navigable reaches. The Congo Basin—the land whose waters drain to the river—is the world's second-largest river basin by area, after the Amazon, according to hydrological research.

River channels and tributaries are important transport arteries in a region where road connections are limited. Research on the basin describes the river system as a source of water for drinking and irrigation and as a resource for hydropower, as well as a route for travel and trade. At Malebo Pool, a broad expansion of the lower river, Kinshasa and Brazzaville stand on opposite banks; the cataracts downstream separate this inland navigation area from the seaport at Matadi. The river therefore links communities and markets, but its rapids also shape where boats can travel.

The river should be distinguished from the broader basin around it. That basin includes a mosaic of rivers, tropical forests, savannas and wetlands across Central Africa. WWF describes its forests as exceptionally rich in wildlife and important for carbon storage, while scientific studies identify basin water and ecosystems as significant to regional and global environmental processes. These natural systems support people as well as wildlife. The basin is also comparatively understudied hydrologically, making local research and long-term water observations important for understanding its resources and how they may change.