Caño Cristales, The River Of Five Colors, Serrania De La Macarena, Meta, Colombia

A unique biological wonder, Caño Cristales has been referred to as "the river of five colors", "the river that ran away from paradise", and "the world's most beautiful river".
For most of the year, Caño Cristales is indistinguishable from any other river: a bed of rocks covered in dull green mosses are visible below a cool, clear current.
However, for a brief period every year, the river blossoms in a vibrant explosion of colors. During the short span between the wet and dry seasons, when the water level is just right, a unique species of plant that lines the river floor called Macarenia clavigera turns a brilliant red. It is offset by splotches of yellow and green sand, blue water, and a thousand shades in between.
This only happens for a brief period in between seasons. During Colombia's wet season, the water flows too fast and deep, obscuring the bottom of the river and cutting off sunlight that turns the Macarenia clavigera red. During the dry season there is not enough water to support the dazzling array of life in the river. But for a few weeks from September through November, the river transforms into a veritable living rainbow.