Which South American river is the world's largest by discharge volume of water?

The South American river with the world’s greatest discharge volume is the Amazon River.

The Amazon carries roughly 215,000–230,000 cubic metres of water per second on average into the Atlantic Ocean. Its basin covers about 7 million square kilometres across several countries, including Brazil, Peru, Colombia, Bolivia and Ecuador. Seasonal rainfall and thousands of tributaries feed its immense flow.

The Madeira, Negro and Japurá are major Amazon tributaries, not rival answers to this question. The Paraná and Orinoco are also enormous South American rivers, but their average discharges are much smaller. “Largest” here means water volume or discharge, not necessarily length.

The Amazon’s length is a separate and disputed topic. Depending on which headwater is treated as the true source, it is described as either the world’s longest or second-longest river system, competing with the Nile. Its discharge record, however, is not seriously disputed.