Major rivers in the Oriente include the Pastaza, Napo, and Putumayo. The Pastaza is formed by the confluence of the Chambo and the Patate rivers, both of which rise in the Sierra. The Pastaza includes the Agoyan waterfall, which at sixty-one meters is the highest waterfall in Ecuador. The Napo rises near Mount Cotopaxi and is the major river used for transport in the Eastern lowlands. The Napo ranges in width from 500 to 1,800 meters. In its upper reaches, the Napo flows rapidly until the confluence with one of its major tributaries, the Coca River, where it slows and levels off. The Putumayo forms part of the border with Colombia. All of these rivers flow into the Amazon River. The Galápagos Islands have no significant rivers. Several of the larger islands, however, have freshwater springs.