River, northwestern South America. Rising in southwestern Colombia, it is about 980 mi (1,575 km) long and flows southeast through tropical rainforests, where it forms a large section of the border between Peru and Colombia. It crosses the border into Brazil, where it is known as the Içá and empties into the Amazon River. It is navigable for almost its entire length and is a major transport route, especially for the rubber produced in the region
{i} river in South America rising in the Andes that flows from south Colombia into the Amazon in northwestern Brazil (the river forms the border of Colombia with Ecuador and most of the border of Colombia with Peru)