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Our Amazing Biobay

with: Mark Martin Bras, Lirio Marquez, and Tom O’Grady Jr.

There are few places in the world that classify as bioluminescent “bays”. Puerto Mosquito, Vieques’ bioluminescent bay, is considered by many to be one of the hidden wonders of the world, having been declared the brightest in the world by Guinness World Records. The experience of taking a guided tour should absolutely not be missed if you are visiting. It is an experience that will stay with you a lifetime.


One can only imagine what the Taíno Indians thought of the glowing waters of the bay. Elders of the community tell stories of how the bay glowed much brighter than it does now, probably due in part to less light pollution at that time. Named Caño Hondo, la Laguna and la Bahía by the locals, the bay has traditionally been used by the local fishing community and their families as a source of food and baitfish, and as a safe harbor for boats during a storm. The bay once provided oysters, and families would collect them from the roots of the mangroves. It was said that the bay could be crossed side to side in the shallows and fishers would walk the bay rather than fishing by boat. Locals named parts of the shoreline after those who frequented the area such as Playita Don Flores and Felix Dones lagoon.

Tourism on Vieques grew in the 1980s and the Biobay became a main attraction.  People came to the bay with local fishers in little dinghies to see what was then a secret. Sharon Grasso began the electric boat tours and soon several kayak operations popped up. At one point a boat called the Moonglow departed from Esperanza at night, travelling to the mouth of the bay from the Caribbean Sea.

The bay and surrounding areas received the designation of a Natural Reserve on June 1, 1989. This was done through a combination of efforts spearheaded by the VCHT and their president at the time, Myrna Pagan Connelly, the Department of Natural and Environmental Resources and the Puerto Rican senate.

The Science

The magic of the Biobay is created by single cell organisms called Pyrodinium bahamense (whirling fire of the Bahamas),  a type of luminescent dinoflagellate. This single cell microscopic plankton is able to convert chemical energy into light energy by synthesizing luciferin which, when mixed with the enzyme luciferase, plus oxygen, produces a bluish-green light. The glow is thought to be a defense mechanism.  The highest concentration of  dinoflagellates in the bay to date was 938,041 per gallon. The concentration varies over time and even at a fraction of that concentration, the Biobay bedazzles.

The Ecology

There are several conditions that make Mosquito Bay the ideal environment for the dinoflagellates to exist in higher concentrations than anywhere else in the world.

A majestic mangrove forest, seagrass beds, a coral reef and neighboring lagoons have combined to create and protect one of the most delicate and unique ecosystems on earth. The lucky location and formation of the bay are key factors. A narrow, shallow mouth traps the water inside and keeps the high concentration of dinoflagellates from being washed out of the bay. The prevailing winds blowing east to west across the mouth of the bay also keep the organisms inside. The specific water quality that makes up the secret recipe of the bay’s primordial soup is perfect, with just the right mixture of salinity, temperature, nutrients, and other components yet to be revealed.  Finding out the recipe is the quest of many people who study the bay, but one thing they all agree on: the amount of factors, variables and components balanced in this fantastic ecosystem is mind-boggling.

Dark Events

In January of 2014 the Vieques Biobay stopped glowing for several months.  While a cause for alarm and a detriment to tourism, it is not uncommon for bioluminescent bays throughout the world to go dark for a few days or weeks creating a “dark event” on the bay. In Vieques, research found that there were 200 bahamense parts per liter compared to 75,000 parts per liter in 2011. Factors that can affect the concentration of dinoflagellates are weather related (winds, tides, rains) and changes to its hydrology and, of course, contamination.

In the context of climate change, scientists have been looking into its possible effects on water level, temperature of air and water, ocean acidification, and other major events such as increased sargassum seaweed. Fortunately, logical minds have recognized the effects of human interaction with the bay and efforts have been underway to minimize and/or prevent dark events.  Listed below are conservation efforts and protocols that exist to protect the bay.

  1. Installation of permanent solar powered monitoring station by the USGS to measure real-time parameters.

  2. Reduction of sediment, pesticide runoff and nutrient loading in the bay.

  3. Implementation of erosion and sedimentation control on road, parking area and walkways.

  4. Reevaluation of the bay’s usage capacity.

  5. Increased training for Bay tour guides and operators such as first aid, CPR, environmental interpretation, etc., including the coordination of resources and venues.

  6. Cooperative collaboration with the operators, guides, VCHT and DNER to protect the bay into the future.

  7. Three-day moratoriums to prohibit tours to the bay on the day before, during and after full moon.

  8. Adherence to the no-swimming policy to reduce/eliminate pollution.

  9. Evaluation of the hydrology of the area and implementation of restrictions on land clearing or plant removal.

  10. Creation of educational outreach for light pollution Law 218 detailing requirements for surrounding barrios.

  11. Weekly monitoring of water quality and plankton counts in the bay carried out by VCHT.

Protectors of the Bay

The Vieques Bioluminescent Bay Natural Reserve is co-managed by DNER and VCHT. The lands belong to the National Parks Company (NPC), the Puerto Rico Industrial Development Company (PRIDCO) and DNER, while other assets are of public domain.

Mark Martin Bras, Director of Community Relations & Field Research at VCHT, whose name is synonymous with the bay, has worked tirelessly for more than 12 years to study and protect it. His efforts creating educational outreach to children and the award-winning summer Manta camp for kids will resonate far into the future. Tours of the bay are also offered by VCHT and collaborating operators.

Biobay tour operators and guides play a crucial role in protecting the bay and ensuring on a daily basis that visitors do not impact the bay in a negative way. They are the nightly guardians of this treasure as well as your escort to experience nature as you have never seen her before. Continued research, education and environmental consciousness have led to cooperative collaboration between the operators and guides and the VCHT and DNER. They are working together to ensure the bay continues to glow.


The Biobay has been revered and respected for many years by many people including locals, visitors, students, guides and scientists, and it is people who are protecting and caring for it on a daily basis. Yet, it is safe to say that, over time, people do the most harm to these dinoflagellates and their home.  The attraction of this must see, bucket list, once in a lifetime destination could also become its demise. We have seen what people have done to destroy other bays.  It inevitably means the loss of needed tourism activity and, most importantly, a stunning piece of nature.

Proactive steps have been taken to guard the bay for the future but we can’t do it without your help.  As a visitor to an island dependent on tourism, you can help. Support our efforts to protect this natural wonder by visiting the VCHT. Leave a donation, sponsor a child for summer camp, shop in the gift store, or simply share your experience with a friend and pass on the magic.

The most important thing you can do is to book your tour through one of the licensed tour operators listed on the following page. You as a traveler have the power to help determine the conservation and survival of this wonder by abiding by the rules meant to protect it.

The relationship between dinoflagellates and humans is a delicate one, requiring diligent attention to the conservation of the Biobay while sharing its beauty with our visitors. It is our hope that all locals and visitors will embrace this challenge for current and future generations.

General Information About Biobay Tours

Trips are not cancelled for rain unless it is a serious storm. Check with the your guide/company about their cancellation policy. Basic skills of kayaking are a plus. If you have never kayaked before tell the company that you are booking with before you make your reservation. Many guides will tie up to your kayak and tow you if you don’t feel comfortable, but they aren’t always available to do this. Companies recommend to not bring electronics or cell phones and are not responsible for any lost or damaged items. Trips are not scheduled the day before, during or day after full moon so plan accordingly. Trips generally take 2 hours. No flash photography is allowed on the Bay. Group discounts are available. You must call to reserve and it is best to pay with a credit card over the phone so you don’t need to carry cash or the credit card with you to the bay. Be on time.

ABE’S Snorkeling and Biobay Tours 787-741-2134 Kayaks: 2 person or 3 person Group size: 40 Guides: 1 per 6 – 10 people Meeting Location: Sunbay – middle parking lot


Bieque Eco Trips

787-922-2701 Kayaks: 2 person clear bottom Group size: 10 Guides: 2 guides per tour Meeting Location: Sunbay 3rd parking lot


Black Beards Sports

787-741-1892 Kayaks: 2 or 3 person kayaks Meeting Location: W Resort or Green Store Group size: 10 Guides: 2 guides per tour and one on shore


Blue Waters Caribbean Adventures

844-210-2922 Kayaks: 1 or 2 person Meeting Location: Sunbay 1st parking lot Group size: 10 Guides: 2 guides per tour


Din Din’s Bio Bay Tours

787-448-5931 or 787-741-2574 Kayaks: 2 or 3 person Meeting Location: Green Store Esperanza Group size: 10 Guides: 2 guides per tour


Fun Brothers

787-435-9372 or 787-741-0151 Kayaks: 2 person clear bottom Meeting Location: Fun Brothers Hut in Esperanza Group size: 10 Guides: 2 guides per tour


JAK Water Sports

787-644-7112 Kayaks: 2  person clear bottom Meeting Location: first parking lot in Sunbay Group size: 10 Guides: 2 guides per tour


Melaya’s Tours

787-222-7055 Kayaks: Clear bottom and 2 person Meeting Location: Esperanza Malecon or Green store Group size: 10 people 1 -2  guides per 10 people

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