[5] The Ruzizi is a young river, formed about 10,000 years ago when volcanism associated with continental rifting created the Virunga Mountains.

Along its upstream reaches, the river forms part of the border between Rwanda on the east with the Democratic Republic of the Congo (DRC) on the west.

The Ruzizi flows into Lake Tanganyika, which overflows into the Lukuga River about 120 kilometres (75 mi) south of Ujiji.

[12] The Ruzizi River lies along the western rift, which includes, from north to south, lakes Albert, George, Edward, Kivu, Tanganyika, Rukwa, Malawi, and others.

[14] Ruzizi I and II are operated by a tri-national company (Burundi, Rwanda and Democratic Republic of the Congo) owned by the Economic Community of the Great Lakes Countries.

[14] On January 16, 2020, the African Development Bank allocated €8 million for technical assistance on the Ruzizi IV hydroelectric project.

The swamps' total area in Burundi has been estimated at 12,000 hectares (30,000 acres) with reeds varying in height from 2 to 4 metres (6.6 to 13.1 ft), depending on the degree of inundation.

[6] A widely publicized man-eating crocodile, Gustave, roams the banks of the Ruzizi River and the northern shores of Lake Tanganyika.

[16] In the film documenting Gustave ("Capturing the Killer Croc"), the narrator states that "In the 1950s, buffalo, elephants and common warthogs inhabited the plain; but they were progressively exterminated by man.