The Amazon River is the longest river in South America according to the standard geographic measurement.
The river rises through the Andes and flows generally eastward across Peru, Colombia, and Brazil before entering the Atlantic Ocean. Its enormous drainage basin covers about 7 million square kilometres, making it the largest river basin on Earth.
The Amazon carries more water than any other river. Its discharge at the Atlantic is greater than the combined discharge of several other major rivers, including the Ganges, Congo, and Mississippi. Seasonal flooding creates extensive wetlands and supports remarkable biological diversity.
A long-running debate compares the Amazon with Africa’s Nile because researchers have used different definitions of a river’s source and mouth. Under widely used modern measurements, many studies identify the Amazon as longer, while older references often list the Nile first. The answer here refers specifically to South America and the standard modern geographic view.