The Aguarico River is a river in northern 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 kilometers, of which the last 50 kilometers 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.
The Aguarico river is a river that flows almost completely by the province of Sucumbíos, in the north of Ecuador, being the main river of the province. In its average course it flows closely near the Reserve of Production Faunística Cuyabeno. In the last part of its course it flows near the Ecuadorian-Peruvian border. Finally it ends at the Napo river, in the same border, a little over the locality the town of Pantoja in Loreto, Peru.