Few natural wonders can match the magic of Mosquito Bay in Puerto Rico. Nicknamed Phosphorescent Bay, this Caribbean lagoon lights up in a neon blue glow thanks to millions of bioluminescent dinoflagellates suspended in the water. Take a nighttime tour and Mosquito Bay transforms into a shining aquatic galaxy.

What Causes the Glow in Mosquito Bay?

The glow comes from tiny plankton called Pyrodinium bahamense, a species of bioluminescent dinoflagellate. When disturbed, they produce a flash of blue light. Each tiny organism emits a tiny light on its own, but collectively the bay glows in patterns according to the movement of the water.

Prime Conditions for Bioluminescent Algae

Several factors make Mosquito Bay the ideal habitat for these light-up plankton:

  • Warm tropical waters around Puerto Rico where the dinoflagellates thrive
  • Sheltered cove limits water flow and ocean currents, allowing the organisms to multiply
  • High concentration of Pyrodinium bahamense, up to 10 million per gallon of water
  • Bioluminescent plankton season lasts from March through October

Night Tours on Electric Boats

The best way to experience the glowing bay is via electric tour boats that minimize disruption to the dinoflagellates. Local operators lead night trips taking visitors into the heart of the bioluminescent waters. As the boat gently moves through the bay, glowing neon blue trails shine in the wake.

A Natural Light Show

Few sights in nature can inspire the same sense of wonder as Mosquito Bay’s bioluminescent displays. Plan a visit to Puerto Rico’s Phosphorescent Bay to witness the glowing sea in one of Earth’s magical hidden gems.