The Caño Cristales is a river of Colombia about 100 km long that is located in the Sierra de la Macarena. It was called the “River of five colors” or the most beautiful river in the world. Normally, the Caño Cristales is indistinguishable from another river. However, for a short period each year, thanks to its red, yellow, green and blue algae, the river "flourishes" in a rainbow of colors. It can be said that the river is the biological heritage of humanity.