Beni

River in northeast Bolivia. Formed by several smaller rivers flowing down from the eastern range of the Andes, the Beni flows west to east through dense jungle country to join the Madre de Dios River at Riberalta. Later it joins the River Marmore at Villa Bella on the Brazilian frontier. It is shallow, meandering, and slow-moving, widening in many parts to almost 1 km. The Beni is navigable for most of its length.