CC BY-SA 4.0, Wikimedia Commons (USDA, DRNA PR)Wildlife· Vieques· Virgin Islands (BVI, USVI and Spanish Virgins)
Mosquito Bay Bioluminescent Bay
18° 6.1′ N · 65° 26.7′ W
Puerto Mosquito, a mangrove-ringed lagoon east of Esperanza that holds the world's brightest recorded bioluminescence: every paddle stroke and fish trail flares electric blue from the dinoflagellate Pyrodinium bahamense. It is a National Natural Landmark and one of three year-round bio bays in Puerto Rico.
Practical
Coordinates from Wikipedia. Do not take the yacht or the dinghy in: Coast Pilot 5 gives only 2 to 3 ft in the narrow entrance, with a sunken rock on its west side, and the bay is a protected natural reserve where swimming is not allowed. Visit on a licensed guided tour (kayak, clear-bottom kayak or electric boat) from Esperanza; operators include Black Beard Sports and others, and Sail Caribe and Puerto Rico Ferry both recommend booking ahead. Go on the darkest nights: tours are often suspended for two or three days either side of the full moon, and moonlight washes the glow out (Wikivoyage). Skip sunscreen and DEET-based bug spray before the tour. The bay is managed by Puerto Rico's Department of Natural and Environmental Resources with the Vieques Conservation & Historical Trust; Hurricane Maria (2017) damaged the mangroves at the mouth and restoration continues. The Vieques National Wildlife Refuge's Puerto Mosquito trail (2.5-mile triangle hike, moderate) leads to an observation platform over the bay.
Best for
The single unmissable night on Vieques
Season
Year-round; best around the new moon, avoid the days around full moon