This story originally appeared on Travelandleisure.com.
The Caño Cristales river in La Macarena, Colombia is dubbed the “River of Five Colors” and “Liquid Rainbow” because of the many colors you can see below the clear waters. Bright greens, yellows, reds, and purples appear to be flowing down the river depending on the light and water conditions, according to Insider.
Sometimes, the river can also appear a bright blue, hot pink, orange, or a deep maroon, according to the BBC.
But it’s not magic that makes this river look so vibrant. According to Algae World News, it’s the macarenia clavigera plant, which is a particular aquatic plant that’s different from algae or moss. The right water level and weather can make a big difference in what colors you can see on any given day.
Besides being beautiful, the plant is also very sensitive to its environmental conditions. The best time to go is when the weather is bright and sunny, so light can reflect the colors. The waters must be high enough for the plants to thrive, but not so high that you can’t see the river bottom, otherwise they’ll die and turn brown, according to the travel website, Rove.
Generally, the colors are at their peak vibrancy between July and November. According to Atlas Obscura, to get to the river, travelers must first fly into Villavicencio, in central Colombia, then charter another plane to La Macarena. There, travelers can find a guide to take them to Serrania de la Macarena, the fairly isolated mountain range where you can access the river.
Not only is the rainbow river an excellent photo opportunity, you can also go swimming in certain parts. Only 200 people are allowed to swim per day, however, in order to protect the picky plants.
Next time you go on a South American adventure, be sure to pack your suit and a waterproof camera. This is a sight that shouldn’t be missed.