The Pozuzu, flowing eastward from the Knot of Cerro Pasco, joins the Pachitea, which is the most important northern affluent of the Ucayali.
The rivers forming this system are the Maranon from Puerto Limon to Tabatinga on the Brazilian frontier (484 m.), the Japura, Putumayo, Javary, Napo, Tigre, Huallaga, Ucayali, Pachitea, Jurua, Purus, Acre, Curaray and Aguarico all navigable over parts of their courses for steamers of 4 to 8 f t.
From Puerto Bermudez, on the Pachitea or Pichis river, the terminus of a government road and telegraph line, a wireless system connects with Massisea on the Ucayali, and thence with Iquitos, on the Maranon-a distance of 930 m.
Above the junction with the Pachitea river as far as the river Tambo, 770 m.
Senor Torres, who explored the Alto Ucayali for the Peruvian government, gives it a length of 186 m., counting from the mouth of the Pachitea to the junction of the Tambo and Urubamba.