The Rio Purus is one of the great rivers of the Amazon Basin, winding through the states of Acre and Amazonas in Brazil before joining the Amazon River. It is renowned as one of the most sinuous rivers in the world — its length following its curves is more than double its straight-line distance, creating an extraordinary labyrinth of oxbow lakes, floodplain channels, and backwater habitats that support exceptional biodiversity. For most of its navigable length, the river maintains a remarkably uniform width, and for roughly 800 miles (1,300 km) of its course, depth never drops below 45 feet (14 m), making it a deep, powerful lowland river rather than a wading fishery. Its elevation is extremely low — only about 107 feet (33 m) above sea level some 590 miles from its mouth — reflecting its character as a slow-moving, lake-flooded drainage system through one of the most biodiverse regions on Earth. The river supports a thriving commercial and sport fishery, with key fishing cities including Boca do Acre, Lábrea, and Rio Branco along its course.