3 hidden gem bio bays in Puerto Rico

Shimmering like a mermaid, I swam under the Caribbean moonlight. The waters warm with the help of my glowing, microscopic friends. I’m not alone in the depths of the Caribbean Sea. I’m surrounded by glowing bursts of blue-green light that pirouette and sashay in the dark waters around me.

The glittering waters I’m swimming in are known as a bioluminescent bay and can be found all over the world. My favorite place to experience this natural phenomenon? Puerto Rico.

Bio bays in Puerto Rico are among the elite and rarest natural beauties. I always look back on these sparkling wonders with such fondness.

What are bio bays?

Bio bays are essentially bodies of water populated with small organisms that give off light when the water around them is agitated. These organisms are called dinoflagellate, which contain chemiluminescence that gives them the power to glow.

Chances are, you’ve caught a glimpse of chemiluminescence in the wild. This is the same natural chemical found in fireflies and other bioluminescence creatures around the world, such as glow worms often found in Australia and New Zealand.

If you have seen the night sky speckled with meandering fireflies, watching the waters in a bio bay has a similar effect, even if photos suggest otherwise.

Bio bays often photograph blue due to the longer exposure needed for cameras to capture the quick bursts of light. In-person, bio bays glow when the water is agitated and are more green in color. The light bursts last no more than 1/10 of a second, so these creatures make their surrounding appear as if they are sparkling or glittering.

For centuries, creatives have swooned over bioluminescent creatures and have incorporated their uniqueness into their works. Popular books and movies that have included bioluminescence ecosystems are Moana, Avatar, Life of Pi and Twenty Thousand Leagues Under the Sea.

Worldwide, it’s unclear how many bio bays there are. Bio bays are fragile ecosystems, and with the rise of tourism, some bio bays have been destroyed completely. Tourists have also reported sightings of bio bays in Australia, Thailand, Vietnam, Japan, New Jersey and Washington in the USA.

Yet, most publications and resources claim that there are only five bio bays worldwide, including the three bio bays in Puerto Rico. With this is mind, it’s even more impressive that Puerto Rico has been able to nurture and protect these rare and fragile bioluminescent bays.

View of an island off the coast of Puerto Rico, home of three of the world’s bioluminescent bays.

Where are bio bays in Puerto Rico?

Puerto Rico is a glimmering hidden gem in the Caribbean that boasts some of the best bio bays in the world. There are two bio bays located on the mainland, as well as a more popular bio bay located on the nearby island of Vieques.

La Parguera bioluminescent bay

Discovering this bio bay in Puerto Rico, was a complete accident. La Parguera is a small coastal city that became popular due to its proximity to the coral reefs and protected marine areas off the coast including its famous bioluminescent bay.

These are a few reasons why this bio bay in Puerto Rico is my favorite. It usually captures tourists’ attention because it is the only bio bay in Puerto Rico that tourists are able to swim in. Although, that doesn’t mean you should.

La Parguera bioluminescent bay is my favorite precisely because it’s a hidden gem and less frequented by tours. On my snorkeling tour and time spent in the area, I got to experience the Caribbean waters in a personal and unforgettable way.

Editor’s note:

Read more about how to sustainably experience this unique experience in the “Can you swim in bio bays in Puerto Rico” section of this article.

How to get there?

La Parguera is situated on Puerto Rico’s southern coast. It’s located less than an hour from Ponce, which is famous for its deep roots in history and art. I stopped at La Parguera on my 2-week road trip and wanted to explore more marine life that calls Puerto Rico home.

Puerto Rico does not have public transportation available throughout the entire island, so renting a car is necessary.

Numerous locals recommended heading to La Parguera for its pristine waters and lack of bustling tourism. In fact, La Parguera was one of the quietest cities that I explore while on my trip. Surrounded by natural beauty, many tourists mistakenly overlook this locale.

Tour Recommendations

La Parguera is a coastal city that offers fishing charters in addition to snorkeling and scuba tours.

I booked a sunset snorkeling tour with an option of adding on swimming in the bioluminescent bay. I booked through Paradise Scuba & Snorkeling, which cost me $75 for the 4.5-hour snorkeling tour.

I can’t recommend this tour enough. Not only were the natural wonders unlike anything I’ve experienced, the staff was also knowledgeable and devoted to sustainable tourism.

Tour guides are in the water with you and usher you through the coral reefs. They take the time to point out the different marine life and encourage you to get an up-close look but also respect the environment. Throughout the tour, guides educate snorkelers about the importance of marine conservation while showcasing these natural wonders.

During my snorkeling tour, I admired numerous urchins, shallow coral reefs and plenty of beautiful fish. The best part was taking the tour at sunset, where the marine life was nothing short than active, was seeing the sky turn pink and evaporate into indigo hues as we sailed toward the bioluminescent bay.

My tour also included dinner which was chicken empanadas, something this hungry snorkeler greatly appreciated.

The tour wrapped with us diving into the bioluminescent bay. Our tour guides explained that bio bays don’t shimmer or illuminate light unless the water is agitated. This is why on other tours, such as kayaking bio bay tours, the bioluminescent appears fainter.

Bioluminescent creatures are also greatly impacted by the health of their ecosystem, so it’s extremely important to take the proper precautions before diving in.

In addition to their green glow, bioluminescent bays are also known for their warm aura they give off when agitated. Caribbean waters already are some of the warmest waters, and that does not change after sunset.

Swimming under the constellations in the sky as the sea around me turned into a galaxy of green stars was unlike anything I’ve experienced.

Laguna Grande Bio Bay

On the east side of Puerto Rico lies Fajardo, a growing port city. Fajardo is best known as being a hub for travelers journeying to Puerto Rico’s smaller islands — Culebra and Vieques.

Unlike La Parguera, Laguna Grande bio bay only offers kayak, boat, biking or walking tours to experience the bio bay. Oars or sticks are used to agitate the waters so the dinoflagellate glow.

Editor’s note:

Significant repairs are being made in the wake of Hurricane Irma and Maria. Double-check availability and whether the site is under construction/closed off for conservation purposes before your visit.

How to get there?

Fajardo is about an hour away from San Juan, Puerto Rico’s capital and most popular international airport. The easiest way to reach Fajardo is to rent a vehicle. Although travelers can also take an Uber/taxi to Fajardo and the nearby El Yunque National Park, they are not always guaranteed a return trip. To avoid being abandoned nearly an hour away from San Juan, organize a return trip in advance with your driver.

Tours for Laguna Grande start at $24 for adult, but offer discounts for students.

Vieques is a smaller island located off Puerto Rico’s mainland. Visitors can reach the island via ferry for a few dollars. Vieques is home to one the brightest biolumniscent bay in the world.

Vieques bio bay in Puerto Rico

Off the coast of Puerto Rico’s mainland is the tiny island of Vieques, home to wild horses, some of the world’s most stunning beaches and to another one of Puerto Rico’s biolumniscent bays.

Vieques prized jewel is Mosquito Bay, voted the world’s brightest bio bay by the Guinness Book of World Records. Experts say that there are 700,000 glowing organisms living in each gallon of water in the bay, making it the brightest of the three bio bays in Puerto Rico.

Due to Mosquito Bay’s narrow mouth, less of the glowing organisms are washed out to sea. It is further protected by the growing mangroves that also serve as an ample food sources for the glowing dinoflagellates.

How to get there?

From Fajardo, tourists can island hop from the mainland to the smaller islands of Culebra and Vieques. Ferry tickets are only a few dollars and affordable for budget travelers.

Once on the island, there are white van taxis that can transport visitors to the beaches and preservation areas. Several companies offer guided tours of Mosquito Bay. Some of the most popular are kayaking tours that grant visitors front seat views of the glimmering water.

Paddle your way through the dense mangroves and experience the bioluminescent bay through the clear bottom of your kayak. Tour prices start around $45 and go up to $135 for more immersive experiences.

Sunset in Vieques overlooking Sun Bay.

Should you swim in bio bays in Puerto Rico?

Like most natural phenomena, bio bays are fragile ecosystems that can easily be destroyed. What causes bio bays to deteriorate is pollution and harsh chemicals that kill the dinoflagellates.

During my snorkeling tour in La Parguera, my guides emphasized the importance of washing off before diving into a bioluminescent bay. Bioluminescent organisms are sensitive to chemicals found in everyday lotions, bug sprays and sunscreens, so only jump into the waters if your skin is clean of impurities.

Coral-safe sunscreen should also be rinsed off because of the delicate nature of these ecosystems. When in doubt, just admire from a distance. The waters only need to be agitated to see that sparkling glow and do not require swimming.

Editor’s note:

Recent natural disasters such as Hurricane Maria and Irma have also drastically impacted the marine ecosystems of Puerto Rico, including its bioluminescent bays. Some bays may appear dimmer since the dinoflagellates have been misplaced or harmed during the storms.

Sandy beaches of Puerto Rico in February.

When to plan your visit

Scientists found that lunar cycles also affect how bright bio bays appear to the human eye. Visiting a bio bay during a full moon may seem like a picturesque experience, but it will actually make it harder to see the blue-green, shimmering creatures that are quickly flashing in the waters below. Instead, it is best to visit bioluminescent bays during a crescent or new moon.

The lunar cycle plays a larger role if you are visiting La Parguera or Laguna Grande bio bays in Puerto Rico. These bays are not as bright as the Mosquito Bay in Vieques, so they are more impacted by the size and brightness of the moon.

Most tour operators have lunar calendars on their websites to help you choose the best date for your visit.

On another note, bio bays are a natural phenomenon that are present all-year-round, but tour prices do decrease during the off-season.

Quirky Globetrotter

Hi! I'm Martha! The mastermind behind Quirky Globetrotter a feminist travel blog. Quirky Globetrotter is devoted to telling narratives devoted to female solo travel and hidden gems worldwide with an emphasis on intersectional feminism and how that impacts travel on a global and local level.

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