Puerto Rico’s Magic Bioluminescent Bays Glow in the Dark

Here’s everything you need to know about kayaking or swimming in the bioluminescent bays in Puerto Rico.

One of the most visually striking scenes in “Life of Pi” is when the protagonist is lost in the dark vastness of the ocean when, suddenly, the water begins to glow as a majestic whale comes up for air. And while magical glowing water may seem as unlikely as a truce between a man and a tiger, the phenomenon is very much real.

Called bioluminescence, this miracle of nature can be experienced in many forms and places around the world. But it is perhaps most striking in bioluminescent bays: bodies of water that glow in the dark. While several bays have seasonal bioluminescence, only five in the world are designated as bioluminescent bays because you can witness this marvel year-round. One is in Jamaica. One is in Vietnam. The other three are in Puerto Rico.

We can think of countless reasons Puerto Rico is known as the “Isle of Enchantment,” but if we had to pick one, it would be these magical glowing bays. Here’s what you need to know about bioluminescent bays in Puerto Rico and how you can enjoy each one.

What Causes Bioluminescence in Puerto Rico?

getawaysmadeeasy / Instagram

Bioluminescence is a chemical reaction in organisms that contain luciferin molecules, which produce light when they come into contact with oxygen. In simple terms, some organisms glow when they are disturbed by movement.

Dinoflagellates, a kind of phytoplankton, naturally have this effect. They are present in many bodies of water but not in high enough concentrations to be noticeable.

In Puerto Rico’s three bioluminescent bays, mangroves and geography have formed an alliance to make the perfect conditions for the phytoplankton pyrodinium bahamense to thrive. The bays contain hundreds of thousands of these organisms per gallon of water, creating an otherworldly effect that is unlike anything you’ve ever seen.

How do you choose which bay to visit? We’d recommend going to all three, if possible. But if that doesn’t seem doable, each bay provides an entirely different experience, so you can choose whichever best fits the kind of adventure that you want to carry back with you.

Mosquito Bay

Discover Puerto Rico

Mosquito Bay is Puerto Rico’s most famous bioluminescent bay. It holds the Guinness World Record for being the brightest bio bay in the whole world. Pyrodinium bahamense are found in absurdly high concentrations of around 1 million to 2.1 million per gallon of water. The result is the bright electric blue glow that has made the bay famous.

Phytoplankton is sensitive, and human activity isn’t exactly copacetic to the preservation of delicate environments. To protect this unique phenomenon and the organisms that make it possible, swimming in this bay is prohibited. But you’ll be able to see the effect as you kayak through the area, lighting up the darkness of the water with the movement of your paddle. You can also plunge your hand in to see your own body glowing.

Despite its glowing crown, Mosquito Bay is not the most visited bio bay on the Isle of Enchantment. That’s because it’s the hardest to reach. The bay is on the small island of Vieques, off the northeast coast of the main island. To reach it, you’ll have to fly from San Juan or take a ferry from Fajardo or Ceiba.

Since tours need darkness and happen at night, you’ll need to stay at least one night. If you can wing it, stay three nights to experience the laid-back beauty of Vieques, which even Puerto Ricans fantasize about.

Once you’re in Vieques, book a bio bay tour with Bieque Eco Trips, a company local to the small island that treats the bay with the respect necessary for preserving it.

La Parguera

Discover Puerto Rico

If we had to pick a single bioluminescent bay in Puerto Rico to visit, it would be La Parguera.

Located in the southwestern part of the island, this bay often gets ignored by travelers because it’s the least bright of the three. It makes up for that by being the only bio bay you can swim in.

While kayaking in what seems like electric water is astonishing, there is nothing like plunging into absolute darkness and finding your entire body glowing with tiny green-blue specks. If you take your hand out of the water, you’ll find that these fairy-like specks cling to you for a few seconds, giving you the illusion that you’re emanating light.

Put your goggles on, take a deep breath, and swim down. You won’t be able to see anything except the dots of light around you. It’s the closest you’ll be to swimming in the stars.

On a good day (like the one we got), you’ll also get a perfect view of the real stars up above so that when you’re floating on the water, you’ll feel like you have stars both above and below you.

And to guide you through this excursion through the stars, trust no one other than the experienced and passionate Captain Jorge Hilerio, who everyone calls Cachi, from Paradise Scuba & Snorkeling.

Laguna Grande

Discover Puerto Rico

Located merely an hour away from San Juan, Laguna Grande is the most accessible and visited bio bay in Puerto Rico.

Even travelers who come for a quick weekend getaway can do a night tour of this lagoon, located within a natural reserve. As with Mosquito Bay, the ecosystem is protected, so you’ll be kayaking instead of swimming.

The kayaking tour will take you through mangrove forests, which you can thank for making this miracle of nature possible. The sounds of nature overpower the senses, enhancing the mysticism of the moment. Go with Kayaking Puerto Rico for a professional and locally-led tour.

Laguna Grande is located near the beautiful El Yunque National Forest. We highly recommend spending an entire day in Fajardo if you have time. You can hike, rappel, and zipline in the rainforest during the daytime. Then, you can head to the bio bay at night for a perfect end to your ecotour.

Tips for Making the Most of Your Puerto Rico Bioluminescent Bay Tour

Discover Puerto Rico

Like anything in nature, bioluminescence cannot be controlled by the whims of humans, so you’ll never know for sure just how bright the effect will be when you visit. That said, there are things you can do to boost your chances of getting a very bright glow at the bioluminescent bays in Puerto Rico.

The easiest is to avoid going during a full moon. You’ll still be able to see bioluminescence, but it won’t be as bright as on the dark night of new moons.

If available, we also recommend that you take a tour that starts at sunset. This will allow you to experience the incredible mangroves that surround the bio bays, swim while it’s light and get some gorgeous views of the sunset from the water. A good tour won’t take you to the bay until it’s dark enough, so you don’t have to worry about visibility.

In terms of responsibility, make sure that you wear sunscreen that doesn’t have harmful chemicals, or don’t wear sunscreen at all if you’re going at night. This is suggested even if you’re only kayaking, but is imperative at La Parguera since you will be going into the water. Creams and bug spray are also a no-go.

Our last tip won’t be very popular, but we promise it will end up being a blessing in disguise: Unless you have highly specialized equipment and are a professional photographer, don’t bother trying to capture bioluminescence. The glow is almost impossible to get on camera and, even when it is, images never come close to the real thing.

How is it a blessing to not be able to show your friends and followers the most incredible experience of your life? You’ll actually get to completely enjoy it without worrying about angles, lighting or keeping your gear safe.

In the end, you’ll get back on the boat and feel relieved that you got to fully immerse in the experience of the moment without thinking about how to present it to others.