The Aguarico River (Spanish: Río Aguarico, meaning "rich water") is a river in northeastern Ecuador. It is the main river of the Sucumbíos province. In the last part of its course it is the Ecuadorian-Peruvian border. It empties into the Napo River. It has a length of 390 km (240 mi), of which the last 50 km (31 mi) of its course extend along the natural border between Ecuador and Peru (in the department of Loreto). The lower course of the Aguarico river was finalized and legally fixed as part of the long-disputed Ecuador-Peru frontier according to The Rio de Janeiro Protocol of 1942. Ecuador unilaterally denounced the protocol in 1960, however a new agreement was signed in 1999 validating the pre-existing protocol.