The Rio Tefé is a significant tributary of the Rio Solimões (the upper Amazon River) in the state of Amazonas, Brazil. It flows through the biodiverse heart of the Amazon rainforest, with its basin encompassing the protected Tefé National Forest. The river is characterized by its connection to the vast Amazonian floodplain system, where it widens into a lake-like area at its confluence with the Amazon. This creates a dynamic environment of blackwater streams, flooded forests (igapó), and interconnected lakes, typical of the region's complex aquatic habitats. The resident human population along its banks engages in sustainable fishing, highlighting the river's importance as a resource.