Introduction to the Congo River: Also known as the Zaire River, it is the second longest river in Africa, with a total length of 4,640 kilometers, second only to the Nile River. In terms of flow, the Congo River is the second longest river in the world after the Amazon River. Two major rivers. The Congo River is also the deepest river in the world, reaching a depth of 230 meters. The lower reaches of the Congo River are about 360 kilometers long between Kinshasa and the estuary of the Atlantic Ocean. It passes through a canyon of about 100 kilometers, and the river surface narrows to less than 400 meters. This section of the Congo River flows between the mountains and the basin, and has also formed many waterfalls, including Livingstone Falls.