What Is a Bioluminescent Bay?

Bioluminescent bays are rare coastal lagoons where conditions favour explosive growth of dinoflagellate species. These single-celled organisms contain luciferin, a chemical that produces light when oxidised by the enzyme luciferase. Mechanical disturbance — a paddle stroke, a wave — triggers the flash. Puerto Rico hosts three famous bio bays: Mosquito Bay on Vieques (the brightest, with up to 700,000 dinoflagellates per litre), Laguna Grande in Fajardo, and La Parguera. Conditions needed include warm water, shallow depth, mangrove-lined shores, and minimal light pollution.