Equateur Province spokeswoman Ebale Engumba said Sunday the boat hit a rock early Saturday in northwest Congo. She says 15 people survived among more than 100 estimated passengers.
Another boat tipping in Kasai Occidental Province left 200 people feared dead after the overloaded boat caught fire Saturday evening.
Congo is a vast country of jungles and huge rivers in Central Africa with little more than 300 miles (480 kilometers) of paved road. Many people prefer to take boats even if they do not know how to swim.
The boats are often in poor repair and filled beyond capacity, and the industry is poorly regulated.