These Salt Flats in Puerto Rico Are Cotton-Candy Pink | Travel

In the Cabo Rojo National Wildlife Refuge in southwestern Puerto Rico, a quick walk through a mangrove swamp leads to an unexpected sight: cotton-candy pink water glistening in the sun. This is Las Salinas, the pink salt flats—a 1,249-acre area of two 18-inch-deep natural lagoons that have been altered to mine salt, and an Instagram-worthy destination for the fluctuating pastel shades of the water.

The color ranges from reddish brown to bright pink to cloudy white, all depending on the day and the weather, though more often than not it’s pink. The hue is thanks to a combination of algae, bacteria, salt and water.

An algae called Dunaliella salina is mainly responsible for the water color in the salt flats. Even though it’s in the green algae family, it’s stuffed full of carotenoids—the pigment that gives many orange and red fruits and vegetables their color. In this particular algae, those carotenoids are red. Archaea, a bacteria and prokaryotic organism (meaning it’s a single cell and doesn’t have a nucleus), floats around in the salt flats as well. It has a pigment called rhodopsin that also appears red.

The color of the water depends on the amount of algae and bacteria in the ponds, explains Lilliam Casillas Martinez, a biologist at the University of Puerto Rico at Humacao who has co-authored several studies on the microorganisms contained in the salt flats. “We have rainy seasons, when the salinity levels decrease [because there’s more water in the ponds]. When there’s less salt, the Dunaliella survives and the ponds look brownish-red,” she says. “During the dry season, it gets really salty. The Dunaliella dies and the archaea and bacteria take over. Then it becomes pink, pink, pink.”

Other hyper-salinated spots around the world have a pinkish hue too, like the pink Lake Tyrrell in Australia, the salt ponds in San Francisco Bay, and the Santa Pola saltern in Spain (though this one is more red and brown than pink). But Cabo Rojo has spectacular biodiversity and is incredibly easy to get to—making it great for a quick day trip while visiting the island. 

Salt is mined from the flats regularly—in fact, it’s one of the oldest businesses in Puerto Rico, Casillas Martinez says. When…