Portuguese  Rio Maputo,  river formed by the confluence in southwestern Mozambique of the Great Usutu River (flowing from Swaziland) and the Pongola River (flowing from South Africa). From the confluence it flows about 50 miles (80 km) northeastward to enter Delagoa Bay, 14 miles (23 km) south-southeast of the city of Maputo. It is navigable along its entire course.