Glowing Oceans? Bioluminescent Plankton Are Back!

From June through the summer, coastal waters in the U.S., Central America, Puerto Rico, and parts of Asia will shimmer with the otherworldly glow of bioluminescent plankton—a natural phenomenon caused by microscopic organisms known as dinoflagellates. These tiny, single-celled algae light up when disturbed, creating glowing waves and sparkling shorelines that captivate beachgoers and photographers alike. But there’s a hidden side to this mesmerizing event.

Dinoflagellates don’t just glow to impress us—they use bioluminescence to startle predators. And under the right (or wrong) conditions, these organisms can rapidly multiply, contributing to red tides—massive blooms that stain the water and sometimes release toxins harmful to marine life, coastal ecosystems, and even humans. This year, warming ocean temperatures and nutrient-rich runoff from agriculture are fueling conditions that may make these blooms stronger and more frequent.

While red tides can be dangerous, researchers are also finding ways to harness the light of dinoflagellates for science. Their glowing trails help scientists track bloom activity in real time and could offer a path toward better early warnings or even methods to control outbreaks in the future.

If you’re hoping to witness this breathtaking display, be sure to: Check local marine advisories Consult experts before swimming And keep safety in mind—not all glowing water is safe water.