Vieques Outdoor Activities

Mosquito Bay in Vieques is famous for its bioluminescence due to the high concentration of dinoflagellates, microscopic organisms that emit a bright, glowing light when disturbed. This natural phenomenon occurs because the dinoflagellates produce light as a defense mechanism to ward off predators. Mosquito Bay stands out as the brightest bioluminescent bay in the world, thanks to its ideal combination of conditions: warm, nutrient-rich waters, minimal pollution, and limited boat traffic. The bay's unique ecosystem and the large number of dinoflagellates create a mesmerizing glow when you disturb the water, making it one of the most awe-inspiring natural sights on Earth.

The bioluminescent intensity depends on weather conditions such as rain, tide, moon phase, sunlight and many other natural factors out of our control. Ideally, the best time to visit is around the new moon and during the dry months, December to March with a midsummer dry season June to July.

Yes, you must stay overnight in Vieques if you plan to see the bioluminescent bay. Vieques is an island separate from the main island of Puerto Rico and you must take a ferry or an airplane to get here. There is no transportation off of Vieques Island in the evening after bio bay tours.

DRNA (the Department of Natural Resources in Puerto Rico) regulates Mosquito Bay/Bahía Mosquito and does not allow any tour companies to do tours during the day before the full moon, the day of the full moon, or the day after the full moon every month. Their reasoning is to give the bio bay a "rest" from human interaction each month during a time when the bioluminescence will often be less visible.

DRNA (Department of Natural Resources) regulates the bio bay and no longer allows swimming in Bahía Mosquito in order to minimize human contamination from products like mosquito repellent containing DEET and sunscreens which kill the microorganisms that cause the bio bay to glow. Swimming in Bahía Mosquito is strictly prohibited.

 DEET (found in major insect repellents like OFF and CUTTER) kills the microorganisms that make the bio bay glow. Operators are committed to protecting this beautiful natural resource and do not allow guests to use these products during tours. You can purchase natural DEET-FREE repellents which are very effective against mosquitos.

Mosquito Bay is only open to Vieques tour companies with DRNA permits, not individuals, between the hours of 6 p.m. and 12 a.m. midnight. As DRNA regulation prohibits swimming in Mosquito Bay/Bahía Mosquito, individuals wanting to see the bio bay on their own would also need to have a non-motorized vessel to see the bio bay and would need to navigate in dark conditions. It is safest to go with a reputable and insured tour company with a DRNA permit with guides who can safely navigate the bio bay and explain the biology of the fragile ecosystem there for you.

Vieques is accessible by ferry (~1 hour from Fajardo, which is 45 minutes east of San Juan) or by small plane (~30 minutes from Ceiba). Many day-trip tours from San Juan include round-trip transportation. However, bio bay tours require an overnight stay, as ferry service returns to the mainland by early morning only.