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When you visit Puerto Rico, one of the must-do things is a trip to one of our bioluminescent bays (or bio-bays). Whether you go to Laguna Grande in Fajardo in a kayak, Laguna Grande in an electric boat, Mosquito Bay electric boat in Vieques, Mosquito Bay in Vieques on kayak,or La Parguera in Lajas, you’re sure to have an experience that you will never forget.

In case you want to try to capture some memories of the biobay in pictures, we’ve written a primer for taking photos in the biobay. Note that you’ll need a very steady boat, and a camera with lots of manual settings — you’ll need to be able to control the length of exposure, the aperture setting (f-stop), and the ISO/ASA film speed setting.

The health of the biobays is measured by the number of dinoflagellates per unit of water. That measure translates into how "bright" the bay will be. Mosquito Bay is the brightest, La Parguera is the least bright. The Department of Natural Resources has taken steps to maintain and improve the health of Laguna Grande. And now they are also doing something for Parguera’s bay…

As of July 2023, both the Vieques Biobay and the Parguera Biobay are closed the night before, the night of, and the night after a full moon.

In any case, the biobay is best experienced on a cloudy or moonless night. While we can’t predict if there will be clouds, we can do a pretty good job of predicting the phase of the moon and the time the moon rises and is overhead. Those are the main factors that come into play. In general, it’s best to avoid the 5 to 8 nights prior to the full moon and a day or two after.

The better bio-bay tour operators will be able to tell you in advance if the night you’ve chosen will be a good night, with regard to the phase of the moon and moonrise. Many operators will not even conduct tours on less-than-optimal nights. Others will bring a tarp to use to block out the moonlight.

To help you with your planning, we’re providing the calendar below which indicates the new and full moons, and our opinion of which nights will be better or than others.

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PuertoRicoDayTrips.com assumes no responsibility regarding your safety when participating in the activities described in this article. Please use common sense! If your mother or that little voice in your head tells you that you are about to do something stupid … then don't do it! Read more about Safety →