Bio Bay Lagoon in Las Croabas in Fajardo, Puerto Rico.
Phosphorescence isn’t a phenomenon limited to Puerto Rico, but the island’s phosphorescent bays (there are three of them: one in Fajardo, one in La Parguera, and one on Vieques) are easily accessible with tour operators and provide a memorable experience for visitors who have never experienced this magical nocturnal phenomenon. The bays’ depth and warmth create the perfect conditions for microscopic dinoflagellates to flourish, and these tiny creatures emit light that makes them look like stars in the sky slipped straight into the water. You can kayak through a mangrove channel to reach the bays, guided by an expert kayaker who can tell you more. Lucky visitors might see fish flashing by like neon streaks. Leave your camera in your hotel room; you can’t capture the phosphorescence without special equipment.