"Wide? No, this is not a wide part," says Usiel the guide, standing up in the skiff and gazing across to the far shore of the Ucayali River, a main Amazon tributary. "Maybe half a kilometer." ...

A small plane brought Chapman professor Pilar Valenzuela and student Priya Shah to the village that resides along the meandering, 1,000-mile-long Ucayali River in the Peruvian Amazon jungle.

See All Key Ideas The boat comes to a halt, shuddering against the dirt bank that rises from the edge of the Ucayali River. Sixto, tanned and with a frown cutting deep furrows across his forehead ...

The Ucayali River—a lower extension of the Apurímac River—took over as the designated source for awhile because it was considered the longest tributary flowing into the Amazon. Then ...