Caño Cristales, often dubbed “The River of Five Colors” or “The Liquid Rainbow,” is a natural spectacle found in the Serranía de la Macarena province of Colombia. But what is behind its kaleidoscope of colors, ranging from yellow, green, blue, black to bright red? The answer lies in a unique interplay of geology, ecology, and hydrology.
From a geological standpoint, the Serranía de la Macarena mountain range, where Caño Cristales is located, is a unique convergence of three distinct ecosystems: the Andes, the Amazon Rainforest, and the Orinoco Plains. This confluence has led to a diverse range of rock formations and sediment types, which play a role in the river’s vivid colors. The clarity of the water is a result of the river’s course over a bedrock of solid rock, as opposed to muddy bottoms found in most other rivers. This clear water allows for sunlight to penetrate and reflect off the riverbed, contributing to the vibrant display.
Ecologically, the star of the show is a unique species of aquatic plant known as Macarenia clavigera. This plant clings to rocks in areas of the river where the current is fast, thriving in the nutrient-rich waters. During the brief span between the wet and dry seasons, the combination of increased sunlight and water clarity causes the plant to undergo a metamorphosis. It turns a brilliant shade of red, while other parts of the riverbed remain yellow, green, blue, and black from other algae and mosses.
Hydrologically, the unique characteristics of Caño Cristales can be attributed to its isolation from other water systems. Unlike most rivers, Caño Cristales has almost no fish due to its clarity and the rapid flow of its waters, which result from the steep gradients of the surrounding terrain. Without fish to feed on the plants, Macarenia clavigera proliferates and dominates the riverbed.