Puerto Rico has three different bioluminescent bays.
One of these is the brightest bioluminescent bay in the world.
I spent a lot of time in Puerto Rico’s bio bays during the three years that I lived in Vieques.
In this article, I will cover everything that you need to know about Puerto Rico’s bio bays:
– What is bioluminescence?
– What is a bioluminescent bay?
– How many bioluminescent bays are there in Puerto Rico?
– Where are the bioluminescent bays in Puerto Rico located?
– Which bio bay is the best?
– Is it safe to swim in the bioluminescent bays in Puerto Rico?
– Are you allowed to swim in the bioluminescent bays?
– How do you book a bioluminescence tour?
Bioluminescence is light emitted by living things, or “biological light.”
This emission of light is a type of chemiluminescence, a chemical reaction where light is produced by a living organism.
Fireflies are one example of bioluminescence that you may already be familiar with. However, most bioluminescence is found in organisms that live in the ocean. Glow worms, giant glowing squid, and shining sea snails all contain elements of bioluminescence.
One thing you can be sure of is that no bioluminescent organism provides as interactive an experience as the dinoflagellates (plankton) that occupy Puerto Rico’s bioluminescent bays.
Stephanie Velazquez is a Vieques native and excursion developer for bio bay trips at Salty Spirit, a local tour company owned by her partner Anak Padro. She spends her days organizing private boat trips to Vieques’s most secluded beaches, and her nights around Mosquito Bay.
“Dinoflagellate is the name of the glowing organism,” says Velazquez. “They are a single-celled plankton, a microorganism called Pyrodinium bahamense. They are half animal, half plant. Their bodies contain chlorophyll which helps them prepare food by photosynthesis. Scientists believe that their glow is a defense against their predators,” she shared.
Velazquez pulls her hand through the water, activating the dinoflagellate’s glow on a tour of Mosquito Bay.
When the dinoflagellate plankton is disturbed, they emit a neon blue glow.
Biologists theorize that some fish may have learned to make use of their defensive bioluminescence.
For example, a fish may swim into an area filled with bioluminescent plankton to watch for the smaller fish who prey on them. When the smaller fish swims into the area and bumps into the plankton, its location is given away, and the larger fish can move in to capture its prey.
It is not uncommon to see fish, and even stingrays swimming underwater with a glowing stream behind them on your tour.
A bioluminescent bay (bio bay) is a bay that contains a very high concentration of bioluminescent dinoflagellate plankton.
These dinoflagellate plankton are found everywhere in regular sea water, but they are in a much higher concentration in bio bays.
They drift into the bio bay from the sea, and then get stuck in the bay due to the fact that the bio bay has a small entrance.
With time, these plankton start to multiply inside the bay as they can’t escape. This dramatically increases the concentration level of plankton inside the bay compared to regular sea water.
When the dinoflagellate plankton are moved in the water, pressure is put on their cell-walls. This causes a chemical reaction inside their cells, which then emits light (bioluminescence).
If you move regular sea water, you can’t see the bioluminescence as the concentration of plankton is too low to see light being emitted. However, in a bio bay, the concentration of plankton is so high that you can easily see light being emitted (bioluminescence).
Bioluminescent dinoflagellate ecosystems are rare, but they can be found in warm-water bays that have narrow openings to the sea.
Mosquito Bay contains up to 700,000 tiny dinoflagellates per gallon of water, a statistic that landed the bay a spot in the Guinness Book of World Records.
“A lot of people wonder why Mosquito Bay is the brightest,” said Velazquez. “The entrance of the bio bay is shaped like an ‘S’ and the organisms get trapped in there. The circulation of the water just stops. Before they get sent to the open sea, they have multiplied so many times, it makes it the highest concentration of dinoflagellates in the world.”
Mosquito Bay is surrounded by mangroves, which provides them with a safe nursery away from predators.
There are three bioluminescent bays in Puerto Rico.
They are Mosquito Bay, Laguna Grande and La Parguera.
Each visit to one of Puerto Rico’s bays can be as unique as the habitat itself depending on what nature has in store for you.
I have visited Mosquito Bay during a light rain when the surface of the bay sparkled, seen fish glowing while they swam underwater and visited during the best time when the moon is not visible in the night sky, exposing you to the world’s most luminous marine light show.
Mosquito Bay, located in Vieques, is only about three feet deep in most of the bay, with the deepest section being around thirteen feet.
Below is a video showing Mosquito Bay:
La Parguera bio bay is located at the southwestern tip of Puerto Rico.
This is the only bioluminescent bay in Puerto Rico that allows tourists to swim with the glowing plankton. The visibility of the bioluminescence is much better in the water with a mask (compared to viewing from out of the water).
Below is a video showing La Parguera bioluminescent bay:
Laguna Grande, located in Fajardo, provides visitors an opportunity to kayak through the mangroves and see the bioluminescence in the bio bay.
Below is a video of Laguna Grande bio bay:
Laguna Grande is in the north-east corner of the main island in Fajardo.
The Laguna Grande bio bay is about an hour drive east of San Juan.
Below is a Google Map that shows the location of Laguna Grande bio bay:
La Parguera bio bay is in the south-west corner of the main island in Lajas.
It takes around two hours and thirty minutes to drive to La Parguera from San Juan.
Below is a Google Map that shows the location of La Parguera bioluminescent bay:
Mosquito Bay is located in Vieques, which is a smaller island on the east-coast of Puerto Rico’s main island.
Below is a Google Map showing the location of Mosquito Bay:
Mosquito Bay requires the most planning, but the trip will pay off.
Vieques is located only seven miles off the coast of Puerto Rico’s main island.
You can arrive in Vieques from San Juan via a small commuter plane from SJU or SIG in San Juan, or RVR in Ceiba.
For a more budget friendly option, hop on the ferry from Ceiba. Allow yourself about two hours of driving time from San Juan and buy your tickets here.
Mosquito Bay was named after Puerto Rican pirate Roberto Cofresi’s ship, El Mosquito.
The bioluminescence made for a strategic hiding spot for the popular pirate, as many of his opponents regarded the area to be “black magic” due to the glowing water. They avoided the area completely, leaving Cofresi and his crews to themselves in Mosquito Bay.
After talking to Stephanie, I learned a lot of people hear the phrase “Mosquito Bay” and douse themselves in bug spray to prepare. While there are mosquitos, it’s important to note the namesake isn’t because the bay is overrun with these insects.
“Repellent is not good for the water,” Velazquez cautions. “We ask our guests to wear DEET Free mosquito repellent.”
The brightest bio bay in the world is Mosquito Bay.
Mosquito Bay is undoubtedly the brightest bio bay in the world. It contains up to 700,000 tiny dinoflagellates per gallon of water, a statistic that landed the bay a spot in the Guinness Book of World Records as the brightest bio bay in the world!
Laguna Grande and La Parguera are still good, but less bright compared to Mosquito Bay.
TripAdvisor provides mixed reviews on the experience at Laguna Grande and La Parguera, but they can be more accessible if you plan to stay only on Puerto Rico’s main island.
Yes, it is very safe to swim in the bioluminescent bays.
The concentration of the dinoflagellate plankton in the bio bays is not high enough to be a health hazard.
There are other types of bioluminescence that are not safe to swim in. For example, “Red Tide” is an algal-bloom found in the open sea that is a different type of bioluminescent plankton. The concentration of the plankton in Red Tide is much higher and can be toxic to swim in.
Below is a video showing Red Tide:
“Swimming is not allowed in Mosquito Bay, but people are allowed to touch the water with their hands or splash their partner,” Velazquez shares.
La Parguera is the only bio bay that allows swimming in Puerto Rico.
Over the years, locals have reported the glow decreasing in the bio bays. This is thought to be because of the many visitors to the bays over the years. The Department of Natural Resources has since put in place rules to ban swimming in Vieques and Fajardo to protect the bays for years to come.
You cannot visit Puerto Rico’s bio bays without a permit, and it is best to go with an expert tour guide that can bring you to the brightest spots in the bay.
To book a tour with Stephanie Velazquez and Salty Spirit to Mosquito Bay, visit her website, Salty Spirit.
All tour guides are CPR certified and she suggests bringing a bathing suit, a change of dry clothes, sandals or water shoes and water.
If you are visiting Laguna Grande or La Parguera, you can find the best tour for your budget and time frame and book directly on Viator.
There are three bio bays in Puerto Rico: Mosquito Bay, Laguna Grande and La Parguera.
Mosquito Bay, located in Vieques, Puerto Rico, is the brightest bioluminescent bay in the world.
If you are visiting Puerto Rico, then experiencing the bioluminescence is a must-do activity.
Mosquito Bay is the best and brightest bio bay in Puerto Rico (and the world). It takes more time to get to Mosquito Bay compared to the other bio bays, but it is 100 per cent worth it.
If you are looking for other things to do during your vacation, then I recommend that you check out our article where we cover the top 45 things to do in Puerto Rico.
Writer at PuertoRico.com. After living in Puerto Rico for seven years, I opened a guesthouse in Rincón and welcomed over 400 guests to the island from around the world. When I’m not writing about travel or spending time with my dog, I’m working towards becoming a pilot with dreams of flying around the islands.About the author