most remote headstream of the Nile River and largest tributary of Lake Victoria, rising in Burundi near the northern tip of Lake Tanganyika. It is formed at the confluence of its two headstreams—the Nyawarongo (Niavarongo) and the Ruvubu (Ruvubu River) (Ruvuvu)—which in turn are fed by streams rising in the highlands east of Lake Kivu and Lake Tanganyika, between Congo (Kinshasa) and Rwanda. The Kagera flows about 250 miles (400 km) north and east. In its middle course northward it is the boundary between Tanzania and Rwanda; turning eastward, it forms the boundary between Tanzania and Uganda for some distance and then crosses Tanzania to enter Lake Victoria 25 miles north of Bukoba.

The Kagera River basin, mountainous and dotted with lakes and swamps, lies chiefly in Rwanda and includes Akagera National Park. The river's longest tributary is the Lukarara, the southernmost the Ruvironza (Luvironza). Much of the Kagera is unnavigable; its only port, Kyaka, Tanzania, is served by shallow-draft cargo steamers.