The Amazon River is the longest river in South America, flowing about 6,400 kilometres to the Atlantic Ocean.
Its main stem runs through Peru, Colombia, and Brazil, although the wider Amazon basin extends across several other countries. The river begins in the Andes and reaches the Atlantic through a vast estuary near northern Brazil. Its enormous drainage basin is the largest in the world.
The Amazon is sometimes listed as the world’s second-longest river, behind the Nile, because researchers use different definitions for its source and mouth. Regardless of the measurement method, it has the greatest discharge of any river on Earth. It also supports exceptionally rich freshwater ecosystems and is central to transport, agriculture, and Indigenous cultures in the basin.