The Ucayali River (Spanish: Río Ucayali is the main headstream of the Amazon River.It rises about 110 km (68 mi) north of Lake Titicaca, in the Arequipa region of Peru and becomes the Amazon at the confluence of the Marañón close to Nauta city. The city of Pucallpa is located on the banks of the Ucayali.
The Ucayali, together with the Apurímac River, the Ene River and the Tambo River, is today considered the main headwater of the Amazon River, totaling a length of 2,669.9 kilometres (1,659.0 mi) from the source of the Apurímac at Nevado Mismi to the confluence of the Ucayali and Marañón Rivers:
Apurímac River (total length): 730.7 km (454.0 mi)
Ene River (total length): 180.6 km (112.2 mi)
Tambo River (total length): 158.5 km (98.5 mi)
Ucayali River (confluence with Tambo River to confluence with the Marañón): 1,600.1 km (994.3 mi)
