The Amazon Basin is the world’s largest river basin, formed by the Amazon River and its tributaries.
The basin covers about 7 million square kilometres and extends across parts of several South American countries. Its rivers drain toward the Atlantic Ocean, carrying an enormous volume of freshwater from the Andes and surrounding lowlands.
The basin is not identical to the Amazon Rainforest. It includes forest, flooded várzea, savanna, wetlands, mountains and urban areas. The Amazon River system has thousands of tributaries, including major rivers such as the Madeira, Negro, Japurá and Purus.
The basin’s size results from the broad lowland landscape and the great number of rivers flowing into the main channel. Seasonal rainfall and Andean snow and glacier melt both influence water levels in different parts of the system.