Visiting Our Bioluminescent Bays: What to Bring and What to Expect

Not two. Not five. Fifteen full minutes.

What you are going to see is not as bright as your cell phone screen. A thing you have to understand is that when you first get out there you will look at that water and see almost nothing, and it is totally normal, mostly because the dinoflagellates need movement to get excited and glow. Right about then some people start to worry that they picked a bad night or a bad tour. But that is not what is happening, and I will explain you what is.

If you are kayaking, you have just come from a parking lot with lights, and your guide had a flashlight on you to get you into the kayak. If you are on a boat tour, you were scrolling your phone on the way there. Either way your eyes are still set for headlights, flashlights or a bright screen. They have to adapt to darkness, and that takes about a quarter of an hour, and like it or not you will not be ready to fully appreciate the bay until your eyes are ready.

So do not judge anything in the first ten minutes. Get in, get still, preferably with your eyes closed, and let your eyes catch up. I guarantee it will arrive. Now that you know, please take my advice.

If you are kayaking, avoid looking at the lights and look at the darkest spots you can find as you make your way out, and once you are there, close your eyes for a couple of minutes. And if you are on a boat tour, stay off your phone. Our cell phones have at least 150 nits of brightness and the dinoflagellates only 0.01, meaning our cell phones are an astonishing fifteen thousand times brighter than what we came to see. One look at that bright screen and we have to wait for our eyes to reset for another fifteen minutes. And in a timed experience, time is certainly not on our side.

Another thing you have surely noticed is that every photograph and every video you have ever seen of this is electric blue. And all three hundred plus of my videos are too. But I have a duty to responsibly inform you that this is not what your eyes are going to see. I would rather tell you here than have you floating out there in the dark quietly disappointed.

That said, what you will see is very special, but you are going to see it as whitish sparkles. Maybe you will see some sort of a pale green. But only at its peak does it pick up any hint of blue at all.

Nobody lied to you. In near-total darkness your eyes stop using the cone cells, the ones that read colour, and switch over to the rods, which only read light. Is that not amazing? And the rods are far more sensitive, they are the entire reason you can see any of this, but they do not report colour at all. I must confess I was surprised myself when I did the research years ago, trying to understand why I could not see the blue.

But a specialized camera sensor has no such limitation. It reads the actual wavelength, and guess what, the actual wavelength is blue! So the camera says blue and your eye says white, and now you know that both of them are telling you their own truth.

But what you give up in colour, you get back in something no camera has ever managed to hand anybody. That is what comes next.

Getting into the water is always exciting, but it is once you are immersed that the magic happens. When anyone enters for the first time, instinctively they start stroking their arms back and forth as they tread water, and in an instant the bioluminescence reveals itself.

What we see in those first moments, and through the whole experience, is a halo of sparkles reacting to every movement we make, and it is quite a show. But my years hosting private experiences have taught me that, more than our Tinkerbell moment and a natural light show like none other on earth, the halo’s density and length are also a great measuring tool to gauge what kind of night we are experiencing.

On an average night I have documented the light from the halo running six to ten inches out from our skin, and we can pick out every individual spark in it. Several hundred of them around that one arm, spaced about a quarter of an inch apart. Around each foot too, if you are moving them, but being farther away and four to five feet under the water you can only see the halo. And believe me, an average night is still quite a spectacle.

But on a peak night, the bay transforms into something truly magical and otherworldly, nothing short of something out of the Avatar movie. On those nights the halo pushes out close to two feet, at twice the density, and it stops being sparks altogether. It goes milky, like powder dissolved in the water, and we cannot find the edge of anything anymore. Those are the nights I live for. Those are the nights I truly feel connected, not only physically but in heart and soul, to the universe and our Creator.

Now, armed with this knowledge, you only need to ask yourself one simple question to know what kind of night you are experiencing: can you still see separate sparks of light in a halo six to ten inches off your arm, or is it dense, milky and reaching almost two feet?

This is something I came up with after hundreds of nights in the water showing our guests how to interact with the dinoflagellates. At some point I realized I kept doing the same movement to show them how the sparkles looked outside the water.

Under the pontoon, while holding on to one of the bars on top, I slowly lift my arm out of the water and tell them to look at the tiny specks of light blinking on it, and then I have them do it themselves. They learn quickly that if they go fast, the sparks run off before they get a look at them.

But when done right, they get to see the dinoflagellates out of the water, and it is pretty cool. This happens because some of them stay on your skin and keep blinking up there, on top of your arm, out in the open air. On an average night you can do this and count thirty or forty of them. On a peak night, it is impossible to count, as they are there in the hundreds.

This is the moment when people go quiet. They are mesmerized by the bright glow of something so small we cannot see it with our bare eyes unless it is sparkling. Before doing this, it is water that glows. After it, they realize it is something more than glowing water. It is something sitting on their arm, speaking to them with its tiny specks of light: "I feel you, and like you I too am alive."

The word average is often misunderstood, and I will clarify what I mean when I say it. Average does not mean bad or weak. It means what happens most of the time, what is normal, and I will tell you what such a night looks like.

Almost everyone has seen what a few fireflies do to a dark night. A handful of them, out in the air, at a distance, and the whole night changes. Now imagine yourself in the water instead. It is dark, you are floating, and every single time you move your arm five hundred tiny flashes answer you at once, wrapped right around your skin. Not out there somewhere. On you. Reacting to everything you do.

That is an ordinary night at the bioluminescent bay, and it is anything but an ordinary night. It is also why I explained the word average first. Average in the bioluminescent bay is always described as a remarkable experience by my guests. But I call them average because my context is different from theirs, having seen the bay hundreds of times, both at its peak and at its lowest intensity. That is why I am selective with my words, never forgetting that I am measuring against my frequent visits to it and you are measuring against nothing you have ever seen.

How to read the night, and the moon

At La Parguera and Laguna Grande, seeing any sea life swimming by is not a common sight, but at Mosquito Bay in Vieques you will see it constantly, and it is one of the most unique things that bay does. A fish crosses underneath you and drags a lit streak behind it. This happens almost exclusively because that bay is home to a full ecosystem, and also because on an average night the bioluminescence there is dense enough that anything that moves writes itself across the dark.

But as beautiful as it is when a fish or a stingray swims by, I will be honest about the other side of it. It is spectacular right up until two hammerheads go past ten feet from your kayak, and then it is a very different feeling. I do not want to scare you, because kayak tours there have an almost perfect safety record after decades operating, but if that happened to me, it can happen to you. And all I wanted after seeing them was to get back to shore.

Do not get me wrong, though. It was still worth sitting with for a second, because I acknowledge it was the bay telling us something. The same density that allows is to see a passing fish beautifully out there also shows us exactly what is in the water with us. And what is in the water there is one of the reasons nobody will encourage you to swim in Mosquito Bay.

This is worth writing down, not to discourage you from doing it, but because most people book these tours without thinking about what doing them actually means.

It is a fact that almost ninety percent of the people who experience the bioluminescent bays in Puerto Rico go to Laguna Grande. And it is also true that almost 95% of all the bioluminescent tours in Puerto Rico are also done in them. And at both Laguna Grande and Mosquito Bay the numbers are even higher. The reason for this is not that they are the very best, but that what pops out when anyone searches for a bioluminescent bay is an image of a kayak with some glow below. They are ones most tour desks offer and also the most affordable ones, mostly due to their short format as each operator runs one-hour tours with ten kayaks at a time, twenty people per departure, back to back all night.

That said, kayaking may not be a science, but it is not for everyone either, and most people book without taking that into consideration. Not every visitor has been in a kayak in their lives. And it will not only be their first time, it will be their first time in the dark, and this should not be taken lightly.

You must also know if two of you are travelling together you will share the same kayak, but if there are three of you, or any uneven number, one of you is going out in the dark with a stranger who may also be kayaking for the first time.

Age, mobility and weight all work either for you or against you in a kayak. And if it flips, getting back in over deep water, at night, is not an easy proposition. That's why kayak tours have age restrictions, and for safety reasons most will not allow anyone younger than fifteen, or seniors, to participate.

Once in the kayak, at Mosquito Bay you go directly into the bay, which makes it a straightforward proposition. But at Laguna Grande you first have to get through a mangrove channel about eight feet wide, with kayaks coming the other way at the same time. People often hit each other, and paddles and hulls get hung up in the mangrove roots. All of that happens in darkness before you have seen a single thing, and you must be prepared to comfortably deal with it.

Finally you also have to understand that the clock is shorter than it sounds. The tour is roughly an hour, but ten of those minutes are spent going in and ten coming back out, so realistically you have about forty minutes of the actual experience. Like I said before, kayak tours run every hour, back to back, all night. It is a volume operation, and the visitor’s comfort is not precisely at the top of their priority. But do not get me wrong: it serves its purpose. It is a fun and somehow adventurous way for people to experience the bioluminescence quickly and on a budget, and at that they do a good enough job.

The next level of experiencing the bioluminescent bay is in a group boat tour. At Mosquito Bay only electric boats are permitted on the bay, and there is one operating. It is more comfortable than a kayak, no question, but you can only run your hand through the water from the boat, so it gives you no more interaction with the bioluminescence than a kayak does. What you gain here is comfort, not a more immersive experience.

At La Parguera the group tours go out in regular boats instead, which is also an upgrade in comfort. On these you share a small twenty-foot boat with up to twelve people, or a larger one with up to forty. They sail out to the bay and here is the big gain from the previous tours as in this ones everybody gets in the water, together. It is a far better experience, since you are immersed in the bay and can fully experience the phenomenon, but it is crowded, and booked from San Juan it is both twice as far and around three times the price of a kayak in Fajardo. Honestly, though, swimming instead of kayaking is such a different experience that the drive and the price difference are entirely justified. Both kayak tours and group boat tours have age limits as part of their safety measures.

Then there is a third way to do this, which is a private tour to La Parguera. On these it is only your party, from two to twelve people. No strangers, no surprises, no sharing the boat. These private tours also offer the convenience of an optional door to door service, and while they operate from San Juan, you can arrange for them to pick you up and bring you back to your hotel or Airbnb, all the way to Rincón in the west and Humacao in the east.

These tours also have no age limits, and they are fully guided and built around safety measures no group tour can provide. They generally include snorkelling, with gear included, for close to two hours at a cay beforehand, and the advantage of having somebody in the water with you showing you how to interact with the bioluminescence. These tours also have CPR and water rescue training. Very few also perform the tours in Pontoon boats offering a big shaded area under the boat that guests claim, and I can assure gives them twice more brightness than under the sky on nights with more than 20% moonlight.

Also those same few work with a local partner hotel, which means you can change before going to the boat, shower after the swim, and put on dry clothes so you can have dinner comfortably and drive back to San Juan clean and comfortable, without worrying about whether anything will still be open when you get there.

But perhaps the biggest perk of a few of these private experiences is that you are filmed with the most advanced low light equipment available, the same used by marine biology filmmakers, and it is delivered to you as a keepsake.

These are priced higher, without question. But doing a private curated experience is totally different and the inclusions and comfort details make them worth every cent you pay for them.

Here I give you a list of things you should have with you to get the best possible night at the bay.

• Beach clothes, with your bathing suit already on underneath.
• A towel. Two if you can manage it, one to sit on and one to dry off with.
• Water shoes if you are kayaking. On a boat you will not need them.
• A full change of dry clothes, and a bag for the wet ones. On most group tours you may have to change in the van. Private tours generally have a partner hotel that allows the use of its facilities for this.
• Benadryl, and an EpiPen if you are allergic. You never know what might happen, and if anything does it is better to have something to deal with it.
• Dramamine, if you get motion sickness easily. This is something you must take before getting into the kayak or boat for it to work.
• Soap, if booking a private tour, as only they offer it. Ask first either way.
• Snacks for the ride back. Driving back to San Juan there are only fast food places, and your driver might or might not offer to stop for food. Having them is always a must. Only on private tours will you have dinner after the bay, at the same hotel where you shower and change, so no snacks are needed on those.

Repellent. You will not need it. In three hundred nights I have been bitten on maybe one in a hundred, and it is not even mosquitoes, it is noseeums, which ignore repellent anyway. And the less that goes into that water, the better.

Sunscreen. If you are snorkelling in the afternoon it is off you long before you reach the bay. Same principle: it costs you nothing to skip it.

Your phone and your camera. You can sometimes get a shot, but it is a two-second exposure and it comes out blurry. What you are risking against that blurry photo is the phone itself, because salt water kills them, and an underwater housing that will actually hold up runs around fifteen hundred dollars. Leave it. Most operators have you leave your bag in the van that brought you, since you cannot take it in a kayak or on a boat anyway.

Not at any of the three bays. Some tours will stop at a fast food place on the way out. At La Parguera you come back into a town with ten or twelve restaurants, so if you buy something you can use theirs. Either way, plan around it, because there is nothing at the water. Only private tours with a hotel partnership in La Parguera have facilities before and after.

You are going to get out of that water soaking wet, and unless your tour has somewhere to change, you stay that way. You dry off eventually. The salt does not come off, and that is the part nobody mentions, sitting in air conditioning for two hours with dried salt on your skin and your clothes.

How long you sit in it depends entirely on which bay you picked:

Worth thinking about before you book, and worth asking whether the tour has anywhere to change and shower. Generally only the private tours do.

Most tours out of San Juan eat early, around 4:30, before going out. You get out of the water around 8:00 and there is nothing after that until you are back where you started. If that does not work for you, ask how the timing runs before you book rather than after. Only the private tours build in time to eat after the experience.

The water is warmer at night than you expect. And the bays are saltier than the open sea outside them, so you float more easily than you are used to, which surprises people, in a good way, and matters more than you would think if you are not a strong swimmer.

Where you swim at La Parguera it is ten to thirteen feet deep and the bottom is mud. There is nothing down there. No coral, no urchins, no rocks to catch a foot on, and nothing living that will hurt you.

Mosquito Bay has everything in it, including sharks. Laguna Grande has documented water quality problems, which I will get to below.

One more thing worth knowing about kayaks. They sit low and they carry no lights, and there are boats moving on these bays at night. A boat operator will see another boat long before he sees a kayak. Stay with your group, stay out of open water where boats run, and do not assume you have been seen.

And if somebody in your group does not swim, a life vest solves it, but ask whether the operator carries them, and whether anybody is going to show your people how to use one before they are floating in the dark. Those are two different questions.

Ask about age limits before you plan anything else around this trip. It is the question most likely to end the conversation, and you want to hit it early rather than after the flights are booked.

Most operators will not take anyone under fifteen, or seniors, and honestly they are right not to. On a kayak tour, in the dark, with twenty people spread across open water, nobody can watch a twelve-year-old or an eighty-year-old the entire time. It is not that they do not want your business. It is that they cannot guarantee safety in that format, and they know it.

If you are travelling with your children or with your parents, you need a format built for it, and you need it confirmed in writing before you book. The only ones that will reliably say yes without age limits are the private tours.

Laguna Grande has a documented water quality problem, and it is only fair that you hear about it before you decide.

When the lagoon went dark for nine days, Puerto Rico’s Environmental Quality Board sampled it and found violations of water quality standards for fecal coliform and streptococcus at every single sampling station in the lagoon. Its president said plainly that this reflected contamination from wastewater discharges in the area. The Secretary of Natural Resources also said the same: that wastewater disposal had proven to be the main source of contamination there. Community leaders had also spent years fighting the placement of a sewage pump station built less than a hundred and twenty-five feet from the water.

And here is the part that should concern you more than the readings themselves. Those are the last official numbers, and they are thirteen years old. Nobody is testing that water for coliforms now. Meanwhile the pump station has kept going out of service and coming back, the utility has posted about it many times between August 2025 and this year, and the smell has not gone anywhere.

So the honest answer is that nobody knows what is in that water today, because nobody is measuring it. Read recent reviews before you book. Visitors mention the smell often enough that you should go in knowing what to expect.

Do not take anything for granted when booking a bioluminescent bay tour. Ask these questions.

• Is there anywhere to change and shower, before and after?
• Is dinner before or after we go out?
• How big is the boat, and how many people are we sharing it with?
• How many people go out on each departure?
• Does the guide get in the water with us?
• What are the safety measures?
• Is anyone on the boat certified in first aid and CPR?
• Does anyone have lifeguard or water rescue training?
• What is the minimum age, and do you take older guests?
• Do we go straight to the bioluminescent bay, or do we do something else first? If so, what, and for how long?
• What happens if somebody in our group does not swim?
• How long are we actually in the water, not counting travel?
• Is anybody filming, or do we get anything sent to us afterwards?
• Do we have any place to rinse off or change into dry clothes?
• Do we dine before departing? Do we stop for food on the way back?

Ask these of whoever you go with. The answers vary enormously, and the price does not always tell you which is which.