Bioluminescent Bays, or Bio Bays, are a rare natural phenomenon that must be experienced at least once in your life. A bio bay is a bay that has a high concentration of bioluminescence – in other words, the water glows an ethereal light.

Vieques may have beautiful beaches, and San Juan has its own attractions, but the gorgeous bio bay might just steal the show.

This bioluminescence is caused by single-celled microorganisms called dinoflagellates, who glow briefly in a blue color whenever they are disturbed (when you move or splash the water). One of the best ways to experience it is to kayak the bioluminescent Bays in Puerto Rico.

There are only five bio bays in the world, but Puerto Rico’s bioluminescent bays make up three of them. Best of all, they are easy to visit and available for kayaking after dark.

I’ll let you in on what you should know before visiting these beautiful bio bays so that you get the best experience out of your night kayaking tour.

Bio bay boat engine

Kayak Bioluminescent Bay, Puerto Rico: What to Expect

Taking a kayak tour of a bio bay can be tricky as some factors will influence your experience of Puerto Rico’s bioluminescent bays. Here are a few of them.


1. Set Real Expectations

I’ll start with this one because it is important to know that all those pictures of bio bay you see on the internet, ALL OF THEM are photoshopped. Yes, the water will produce blue-green light, and yes, it looks magical, but it’s never as bright as those pictures make it look.

Bio bay kayaking google image results
Look at all this beautiful photoshop!

In fact, it’s almost impossible to take a good picture while you’re kayaking on the bay because it is too dark and there’s too much movement for a long exposure shot.

For such reason, you’ll see that the images in this post are not the best ones, even on a night kayaking tour. ¯\_(ツ)_/ ¯

This is a natural phenomenon that varies on a daily basis. Maybe you’re lucky and get to see the bio bay in its 100% glow state, or not so lucky where you don’t see anything at all – under 30% glow. So, expect nothing, but hope for the best.

I’ve kayaked a few times on each bio bay in Puerto Rico, and I can say that I’ve had all kinds of experiences, from “meh, the moon is not helping, and the glow is not at its maximum, but it’s still cool,” to “OMFG, I’m tripping in blue microscopic acid!

So far, my best bio bay experience has been Mosquito Gay in Vieques, but yours could be in Laguna Grande or La Parguera!

2. Pick a Bio Bay Based on Your Trip

Part of Puerto Rico’s fun facts is that it has three bio bays. These are:

  • Mosquito Bay in Vieques Island (a small island east of the main island of Puerto Rico)
  • La Parguera in Lajas (southwestern part of Puerto Rico)
  • Laguna Grande in Fajardo (northeastern part of Puerto Rico)

The consensus among most people is that Mosquito Bay is the best bioluminescent bay in Puerto Rico and the world. It’s protected by the Vieques Bioluminescent Bay Natural Reserve, so it’s as well-maintained as it is beautiful.

So is Mosquito Bay worth it? That’s a resounding “yes.” The Mosquito bioluminescent bay is so stunning that it has the Guinness World Record for being the brightest bio bay in the world.

Having said that, it is not guaranteed that the brightness of that bio bay will surpass Laguna Grande and La Parguera on any given day. We are dealing with unpredictable nature, after all.

The glow percentage varies on all of them every single day based on the water temperature, phase of the moon, water currents, and other ecological variables.

In terms of accessibility, Laguna Grande is the easiest to reach as it is the closest bioluminescent bay to bustling San Juan. It’s set just 50 minutes away from the city by car. Due to the accessibility, this is the most touristy of all three.

Mosquito Bay will require you to take a ferry or a short flight to Vieques Island and spend at least one overnight stay for your nighttime adventure there — it’s worth it, though!

On the other hand, La Parguera is the least touristy, but it is within easy reach if you’re traveling on the western side of the island.

Most tourists debate whether to go to Laguna Grande vs. Mosquito Bay. My answer is: if you have the time to go and stay for a night in Vieques, go to Mosquito bioluminescent bay. If you don’t, go to Laguna Grande.

3. You Can’t Swim in the Water… or Can You?

Years ago, swimming was allowed in every bio bay as it’s one of the trippiest experiences you can have.

The water is so warm and the glow so surreal. All you want to do is swim and kick your legs to make all the water around you light up. You’ll feel like you’re in a scene from “Avatar.” It’s an experience I’ll never forget.

Even if you don’t swim, just dipping your hands and removing them quickly will allow you to see the glow dripping off your hands.

These days, though, swimming is restricted to preserve the sea life and ecology of the bays. One of the main reasons swimming is forbidden is to prevent kayakers from dipping in the water with chemicals on their bodies, like bug spray and sunscreen.

Having said this, it is said the Department of Natural and Environmental Resources (DRNA in Spanish) has allowed tour operators to offer swimming with the proper DRNA permit.

In recent years, this seems to have been slowly restricted even further, so you must ask each tour company directly – though it’s more probable they’ll say “no.”

Apparently, Alelí Tours may still allow you to swim in La Parguera (this bio bay seems to be the least restrictive since it is the least touristy).

There is of course the option of sneaking a swim in a bio bay. But Mosquito is the strictest one, so even on your own, you might not be allowed to do it if a tour company or DRNA official sees you (I have friends who have gotten away with it on their own, though).

Kayakers at the bio bay
No, not them…

Swimming on the bio bay is not an “evil thing.” We’ve done it for generations without affecting the waters.

According to marine biologists, most glow variations happen naturally and can change on a daily, monthly, or even yearly basis.

Tour companies are no longer allowing swimming just to limit the amount of chemical pollution they’ve seen with recent mass tourism.

So please, if you are planning on swimming in a Puerto Rico bio bay on your own, ensure you have absolutely no chemicals on your body!

4. Try to Plan Your Trip Based on the Lunar Cycle

The most awesome time to go kayaking on a Puerto Rico bioluminescent bay is when there’s a new moon and it’s completely dark.

While you can enjoy all three bays on any given day, their brightness looks more spectacular when you have a clear night around the new moon. Otherwise, a cloudy night on any other lunar phase will work just as fine.

Should you go during the full moon, the knowledgeable staff from tour companies have their ways to help you see the glow. Usually, by taking a tarp you can put over your kayak to darken the glowing waters under you.

But, preferably, go when it’s a new moon. From experience, the visual impact and glow change dramatically when you have a new moon as opposed to a full moon, and the glow percentage is high enough – 70% or more.

If you want to make sure when’s the best time to go to the bioluminescent bay in Puerto Rico, I recommend checking this Moon Phases Calendar. It can help you plan your trip according to the moon phases.

Bio bay boat engine glow

5. Call the Day Before to Check the Brightness of the Bio Bay

Most tour operators won’t take you kayaking if the water light is under 30%. This is the lowest range where the dinoflagellates concentration makes them visible.

Still, it’s good to call them a day or so ahead of your trip to confirm how bright the bay has been lately.

Hurricanes like Maria, tides, strong winds, water temperatures, and seasons do affect the water light in all three bays at different rates. So if you have the opportunity to scout and plan last minute, call several tour operators on all three bays to see which one is the brightest at that moment.

Many a tour guide in the bio bay areas will give you a percentage scale, while others will give you a numerical scale from 1 to 10, with 10 being the brightest.

Bear in mind that if you’re planning at the last minute, you must take into consideration the logistics of getting there. Getting to Lajas from the San Juan area takes about 2.5 hours by car. Getting to Ceiba takes about 1 hour.

You have to either fly from San Juan to Vieques or drive to Ceiba and take the 1-hour ferry to the island or the 12-minute flight, also from Ceiba. You can’t go wrong with round-trip transportation in Puerto Rico.

6. It’s Best to Book Ahead of Time

Prepare for your trip to Puerto Rico the right way. It’s best to book a bioluminescent bay tour early, especially if you’re going on a holiday weekend, as kayaking is a popular night activity in Puerto Rico.

Check the cancellation policy with the tour company. This is just in case you find a brighter bay like Laguna Grande at the last minute and wish to change your trip with a full refund to a different date or location.

Prices range from $50 to $100+, depending on the type of boating experience or kayak tour you’re looking for.

Bio bay kayakers
Quite honestly, this is more likely how your pictures are gonna look like. ¯\_(ツ)_/ ¯

We might be in the 21st century, where most things can be booked online, like these cheap hotels in Puerto Rico. But it seems like most of these kayaking companies haven’t caught up to this wonderful technological marvel that can ease our travel planning.

Thankfully, some companies do display their tour options on Viator, so I highly recommend booking them immediately through their platform. It costs the same – and sometimes less than on their websites.

The following are links to some of the best of Puerto Rico’s bioluminescent bay tours kayaking with a professional guide:

Bio bay Kayaking during the sunset

7. Book the Later Time Slot

Typically, there are two time slots you can book each day for a kayak tour, one around 6:30/7:00 pm and the other tour group around 8:30/9:00 pm.

Depending on the time of the year, the earlier tour might still be a bit bright when you depart. This will give you the opportunity to see the mangrove forests as you kayak in the twilight. Then it’ll be fully dark once you reach the center of the bay.

On the other hand, the second tour will be fully dark from start to finish, so you won’t see much of the mangrove trees.

Having said this, you only see the glow at its maximum once you reach the center of the bay, so it’s ok to pick either – but most people prefer the latter kayaking slot.

8. Forget About the Pictures

Lastly, leave your camera behind. Get a real feel for Puerto Rico and magical bio bay kayaking without one. You will get wet as you paddle, so anything you carry might also get wet.

Also, as explained before, your cameras and phones won’t capture the glow of the bioluminescent lagoon at night as you see it – even with long exposure. If you use flash, you’ll only see yourself and the kayak in total darkness.

So, enjoy, experience, and live the moment amongst the microscopic plankton to the fullest without worrying about your pictures.

Have you kayaked on any of the bioluminescent bays in Puerto Rico? How was your experience?

Everything You Need To Know Before Kayaking in Puerto Rico's Bio Bays

Images 1, 2, 3, 4, and 5 are from Flickr Creative Commons.
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5 Comments

  1. Wow! What a great guide with so much useful tips. Kayaking in the Puerto Rico bays sounds absolutely thrilling. Thanks for your post.

  2. What a great excursion. I had never heard of bio bays in Puerto Rico. Thank you for a great article, I am going to out this on my bucket list!

  3. In Farjado – Is about a mile to the bay to kayak… and you’ll need to dodge other kayaks, mangrove trees (and they’re crazy roots), huge iguanas, and the tides. Go for the electric boat… 1k times better!

  4. It’s interesting to know that bioluminescent kayaking is described to be a surreal experience. I plan to go on a trip like that because I’m thinking about going out of town with my husband for our anniversary. Kayaking would surely be a fun activity to get into.