The amazing Red River forms a unique landscape against the backdrop of rolling green hills. This unusual view has to be seen to be believed. The small river, called Palquella Pucamayu by the locals, maintains a bright red color for about 3 miles (5 km). The unusual color is explained by the fact that the Red River is formed by run-off rainwater from the Palcoyo Rainbow Mountain, which boasts a unique mineral content. Red color is more visible in the water thanks to a high iron oxide content. Due to the origin of the river, this unusual phenomenon is prevalent during the rainy season.
Even though the dry season (which runs from May to October) is considered the best for trekking near Cusco, there's a chance that the color of the river will be close to brown if you visit during that period. April is the best time to see the Red River in its full glory, bustling with scarlet water.
The Red River joins in with other streams, and eventually, its red color gets dissolved. Downstream it falls into the Vilcamayo River, which flows to Machu Picchu. To visit the Red River, just book a tour with one of the operators in Cusco. The Palcoyo Rainbow Mountain Tour usually includes a visit to the Red River. The attraction is located in the Canchis Province, about three hours southeast of Cusco.