river in southwestern Dominican Republic, one of the nation's three most important river systems. Its headstreams arise on the southern slopes of the Cordillera Central, uniting near Duarte Peak. The river is 80 miles (130 km) long and descends into the eastern San Juan valley, crosses into the Neiba valley, and then turns abruptly eastward to empty into Neiba Bay, off the Caribbean Sea, just north of Barahona. Although the river is not navigable except by small craft, it is economically important because its waters are used extensively for irrigating rice, plantain, sugarcane, beans, bananas, and peanuts (groundnuts).