Bioluminescent Mosquito Bay (Vieques)

This south Vieques beach might not sound like much, but it’s one of travelers’ favorite experiences in Puerto Rico. During the day, Bioluminescent Mosquito Bay is your stereotypical Caribbean hideout — but at night, the sky and waters emit a blue glow from the half-plant, half-animal microorganisms that live there. More than 700,000 bioluminescent dinoflagellates live in each gallon of bay water, and recent travelers have been amazed by just how much visibility these tiny creatures provide.

But avoid visiting the bay during a full moon; the microorganisms aren’t as visible then. Also aim for a quiet approach: “I would definitely go in a group with kayaks-not a motorized boat,” one TripAdvisor reviewer said. “It is very peaceful and beautiful to be on the water at night but the sparkling water is a real treat.”

Though you can visit Mosquito Bay unaccompanied, most suggest you spring for a tour of the area. Mosquito Bay’s official site offers tips on the best nights to visit and lunar calendar information, as well as details on eco-friendly tours. Nightly tours operated by the popular Travesias Islenas Yaureibo range from $35 to $55 per person, depending on which type of tour you choose.