 The country's longest river is the Nyabarongo, which rises in the south-west, flows north, east, and southeast before merging with the Akanyaru to form the Akagera; the Akagera then flows due north along the eastern border with Tanzania.The Nyabarongo-Akagera eventually drains into Lake Victoria, and its source in Nyungwe Forest is a contender for the as-yet undetermined overall source of the Nile.Rwanda has many lakes, the largest being Lake Kivu.