The amazing colours of Caño Cristales come from a plant - a special river plant called Macarenia clavigera that only grows in a handful of rivers in the world. When sunlight hits the water at exactly the right depth and temperature, this plant turns vivid pink and red. Mixed with yellow sand, green algae, blue water and dark black rock, the river becomes a living painting.
The river flows over a rocky plateau called the Serranía de la Macarena, a table-top mountain that has been isolated from the rest of South America for millions of years. This isolation means the area has plants and animals found nowhere else on Earth.
The colours only appear in a narrow window between July and November. In the dry season, the water is too low and the plant can't grow. In the rainy season, the water runs too fast and deep and the sunlight can't reach the river bed. Only in the transition between wet and dry does the river glow.
To visit Caño Cristales, tourists must book guided tours. Only a certain number of visitors are allowed each day, and visitors must stick to stepping stones and walkways so the delicate plants are not damaged. It is a wonderful example of a beautiful place being carefully looked after.