The Caño Cristales river in the Serranía de la Macarena mountains of Colombia

© Jorge Iván Vásquez Cuartas/Getty Image

A river of many hues

Today's photo brings us to the banks of Caño Cristales, the 'liquid rainbow' that cuts a kaleidoscopic path through the heart of Colombia. From June until November, when the clear water is low, the underwater plants that cover the riverbed show off their red, yellow, green and blue hues. The star of the show, as seen in our homepage image, is Macarenia clavigera, a riverweed that can go from bright red to deep crimson or purple, depending how much sun it gets. In August and September, when these flamboyant flora are at their peak, it's a popular nature excursion but, because the river's ecosystem is so fragile, visits are limited to guided tours.