Why Cancun’s white sand stays cool: the parrotfish effect

Picture this: you are strolling barefoot along a beach, the sun is blazing, yet the sand underfoot stays cool. That is not a daydream but an everyday scene on the shores of Cancun, Mexico. While in many places summer sand is off-limits without shoes, here it stays surprisingly comfortable. How does that happen? The answer, unexpectedly, lies with a fish.

The fish that builds the sand

The star of this story is the parrotfish. It lives on the coral reefs near Cancun and feeds on coral, though not quite the way you might imagine. It does not just nibble the surface: it grinds the coral up as it eats, processes it internally, and then releases it as fine, white sand. That very sand covers the local beaches.

Scientists estimate that up to 70% of Cancun’s sand comes from these fish. It is striking to think that a single large parrotfish can produce as much as a ton of sand in a year. In other words, these fish are quite literally shaping the shoreline.

Why the sand stays cool

It is not only about who makes the sand, but also about what it is made of. Cancun’s sand differs from the usual river or seashore mix. It is white and very light. That bright color reflects sunlight well, so the surface does not heat up as quickly.

On top of that, the grains are highly porous, dotted with tiny holes like a sponge. Because of this structure, the sand does not trap heat and lets it dissipate fast. Even if it warms a little during the day, a light breeze is enough to cool it down again.

So what is the secret?

Put it all together—the unusual origin, the pale color, and the airy structure—and you get a natural cooling system under your feet. Walking on this sand feels pleasant even at high noon. It is not magic, just a neat alignment of nature, climate, and marine life.

What if it all disappears?

There is a catch. If coral reefs decline, parrotfish will decline as well. Without them, there will be no fresh sand. Corals are under pressure from pollution, global warming, and mass tourism. Which means those effortlessly comfortable beaches are not guaranteed forever.

A simple fact you probably never considered

The sand you tread in Cancun is the handiwork of a small fish that has no idea it is making people happy. Thanks to it, the beaches are white, soft, and cool. Sometimes the simplest things turn out to be nature’s quiet wonders.