16,708 m3/s (590,000 cu ft/s)[1] The Marañón River (Spanish: Río Marañón, IPA: [ˈri.o maɾaˈɲon], Quechua: Awriq mayu) is the principal or mainstem source of the Amazon River, arising about 160 km to the northeast of Lima, Peru, and flowing northwest across plateaus 3,650 m (12,000 feet) high,[4] it runs through a deeply eroded Andean valley, along the eastern base of the Cordillera of the Andes, as far as 5° 36′ southern latitude; from where it makes a great bend to the northeast, and cuts through the jungle Ande in its midcourse, until at the Pongo de Manseriche it flows into the flat Amazon basin.

As the Marañón passes through high jungle in its midcourse, it is marked by a series of unnavigable rapids and falls.

The Lauricocha and Nupe unite near the village of Rondos to form from their confluence downstream the river that is called the Marañón.

A 552-km (343-mi) section of the Marañón River between Puente Copuma (Puchka confluence) and Corral Quemado is a class IV raftable river that is similar in many ways to the Grand Canyon of the United States, and has been labeled the "Grand Canyon of the Amazon".

It is in dry, desert-like terrain, much of which receives only 250–350 mm/rain per year (10–14 in/yr) with parts such as from Balsas to Jaén known as the hottest infierno area of Peru.

The Marañón Grand Canyon section flows by the village of Calemar, where Peruvian writer Ciro Alegría based one of his most important novels, La serpiente de oro (1935).

One of the first popular descents of the Marañón River occurred in 1743, when Frenchman Charles Marie de La Condamine journeyed from the Chinchipe confluence all the way to the Atlantic Ocean.

[18] The Marañón River may supply 20 hydroelectric mega-dams planned in the Andes, and most of the power is thought to be destined for export to Brazil, Chile, or Ecuador.

[27] Potential ecological impacts of 151 new dams greater than 2 MW on five of the six major Andean tributaries of the Amazon over the next 20 years are estimated to be high, including the first major break in connectivity between Andean headwaters and lowland Amazon and deforestation due to infrastructure.