The Marañón River (Spanish: Río Marañón) is the principal or mainstem source of the Amazon River, arising about 160 km to the northeast of Lima, Peru, and flowing through a deeply eroded Andean valley in a northwesterly direction, 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 Andes, until at the Pongo de Manseriche it flows into the flat Amazon basin.
Although historically, the term “Marañon River” often was applied to the river all the way to the Atlantic Ocean, nowadays the Marañon River is generally thought to end at the confluence with the Ucayali River, after which most cartographers label the ensuing waterway the Amazon River.
The Marañon River was considered the source of the Amazon River starting with the 1707 map published by Padre Samuel Fritz, who indicated the great river “has its source on the southern shore of a lake that is called Lauriocha, near Huánuco.” Fritz believed that the Marañón contributed the most water of all the Amazon’s tributaries, making it the most important headstream.
For most of the 18th–19th centuries and into the 20th century, the Marañon River was generally considered the source of the Amazon. Later explorations have proposed two headwaters rivers of the Marañon in the high Andes as sources of the Amazon: the Lauricocha and Nupe Rivers. The Lauricocha and Nupe unite near the village of Rondos to form from their confluence downstream the river that is called the Marañon.
- Take a boat cruise down the Marañon and explore the Pacaya Samira Natural Reserve.
- Pack raft down the river and camp along the shores of the river Marañon.
4 – 9 Days: Take a river boat cruise or organise a packrafting expedition to explore this part of the Amazon Jungle.