The greatest in volume river on the earth is the Amazon and its river basin is also the largest, as it extends over 6.9 million km2, 5% of the land surface (excluding Antarctica). But the Amazon discharges 6,591 km3 of water into the Atlantic Ocean every year, 15% of the total discharge of all the rivers on Earth.  The reason is that the Amazon basin is located in the equatorial area, where the highest rainfalls of the planet occur. Thanks to the contribution of the Amazon, South America, with 12% of the planet's surface accounts for 24% of the runoff, ie, the water flowing over the surface to form rivers. But 7% of the area of South America that is not part of the Amazon basin contributes only 9% of the global runoff, ie, only slightly above the average.

Evaporation and surface runoff by continents. 

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