Caño Cristales, a series of remote rivers, waterfalls and streams inside the wilderness of Parque Nacional Natural Sierra de La Macarena, has been called everything from 'The River of Five Colors' to 'The Liquid Rainbow.' This is due to a unique biological phenomenon that takes place for a couple of months between July and November when an eruption of algae forms an underwater blanket of bright red. This transforms the crystal-clear water into a river of cabernet that contrasts magically with the lunarscape of ancient, hollowed-out riverbed rock and the surrounding savannah landscape.

Coming here involves some expense, a lot of sweaty hiking and some fairly unexciting meals in the town of La Macarena, but the pay-off is immense. You'll no doubt agree when you dive into one of the numerous swimming holes, waterfalls or natural pools along the river, or come face-to-face with the impressive local wildlife.