The Amazon River has the largest water volume of any river in the world. It has more water than the next seven largest rivers combined.
The Amazon River in South America is the largest river by discharge volume of water in the world, and by some definitions, it is the longest.
The headwaters of the Apurimac River on Nevado Mismi had been considered for nearly a century as the Amazon's most distant source until a 2014 study found it to be the headwaters of the Mantaro River on the Cordillera Rumi Cruz in Peru. The Mantaro and Apurimac join, and with other tributaries form the Ucayali River, which in turn meets the Maranon River upstream of Iquitos, Peru, to form what countries other than Brazil consider to be the main stem of the Amazon. Brazilians call this section the Solimoes River above its confluence with the Rio Negro to form what Brazilians call the Amazon at the Meeting of Waters at Manaus, the largest city on the river.