It straddles the border between Burundi and Rwanda.

In Rwanda, the lake is known as Cyohoha South to differentiate it from the nearby much smaller Cyohoha North 10 miles north in Rwanda.

The lake covers 74 square kilometres (29 sq mi), of which 19 square kilometres (7.3 sq mi) are in Rwanda and 55 square kilometres (21 sq mi) belong to Burundi.

The Nduruma River is fed by the Matonnyanga to the north of Mukerwas colline, by the Runyuiya to the south of Rwimbogo colline and by the Gasuga, which forms between the Kabirizi and Butihinda collines.

[1][a] Lake Cyohoha South just as its cousin Cyohoha North empties into the Akanyaru River via a series of marshlands that connect these lakes to the river.