Lake Kivu on the Rwandan side.
Kivu definition by Webster's New World
Webster's New World College Dictionary Copyright © 2010 by Wiley Publishing, Inc., Cleveland, Ohio. Used by arrangement with John Wiley & Sons, Inc.
lake in EC Africa, on the border of Democratic Republic of the Congo & Rwanda: c. 1,100 sq mi (2,849 sq km)
Kivu definition by American Heritage Dictionary
A lake on the border of Congo (formerly Zaire) and Rwanda north of Lake Tanganyika. It is situated at an altitude of 1,461 m (4,790 ft) and is Africa's highest lake.