The Amazon River is the longest river in South America under the commonly accepted measurement.
The river flows across northern South America and empties into the Atlantic Ocean. Its drainage basin is the largest in the world, covering parts of several countries, with most of the basin in Brazil. The Amazon also carries more water than any other river on Earth.
Its exact length has been debated because researchers disagree about which headstream should count as the river’s true source. The commonly cited figure is about 6,400 kilometres, placing it near the Nile in global length comparisons. Different measurement methods can therefore produce different rankings.
The Amazon is central to the ecology, transport, and human history of the region. Its basin includes the Amazon rainforest, and the river system contains thousands of tributaries, including major waterways such as the Rio Negro and Madeira River.