negro river

The largest left tributary of the Amazon River and the largest blackwater river in the world, flowing from eastern Colombia through southern Venezuela and northwestern Brazil to join the Amazon near Manaus.

The most important river of the Río Negro province in northern Patagonia, Argentina, flowing eastward from the confluence of the Limay and Neuquén rivers into the Atlantic Ocean.

A major river of Uruguay that rises in the southern highlands of Brazil and flows southwestward across central Uruguay into the Uruguay River.