Best Time To Visit Puerto Rico’s Bioluminescent Bays

St Thomas Tours & Excursions

Puerto Rico is an archipelago blessed with all kinds of natural beauty. Valleys, rainforests, waterfalls, beaches and bays — you name it and this dreamy island has it. Most people who visit Puerto Rico are nature lovers who want to spend their holiday outdoors soaking in the sun, exploring the wilderness and seeing unique natural phenomena. 

One of these unique natural phenomena that you can see in Puerto Rico is the bioluminescence of the bays there. If you’re scratching your head while wondering what a bioluminescent bay is, don’t worry! This article will explain it all.

What Is A Bioluminescent Bay?

A bioluminescent bay is an inlet of water in which the water glows. It is a gorgeous natural phenomenon to witness and is one of the reasons so many people flock to Puerto Rico to spend their holidays. 

But how do they occur? Well — it’s actually quite simple. These waters have millions of microorganisms called dinoflagellates that have the capability to glow in the dark. When they produce their own food by a process called photosynthesis, they emit light. This bluish-green light gives the water in these bays a magical glow that older generations attributed to magic or the moonlight. 

Puerto Rico is quite the hotspot when it comes to bioluminescent bays because three of the world’s light-emitting bays are in Puerto Rico. Since these are quite rare, having three in one place is quite a feat.

Best Time Of The Year To Visit Puerto Rico’s Bioluminescent Bays

Mosquito Bay, La Parguera, and Laguna Grande are the three bioluminescent bays in Puerto Rico. However, what is the best time of the year to visit them? Let’s find out.

Since heavy rainfalls adversely affect the glow of the dinoflagellates, the best time to visit the bays is in the dry season. The dry season in Puerto Rico starts from December and goes on until mid-April. 

While you can see the dinoflagellates glow around the year, there’s a good chance that heavy rainfalls in the summer may dull or completely wipe out the glow in these magical bays. So, if you don’t want to take a chance, make sure to stick to the dry season when visiting Puerto Rico’s bioluminescent bays.

Why You Should Keep An Eye On The Lunar Calendar

If this sounds strange to you, don’t worry, you’re not the only one. The visibility of the surreal, blue-green glow of the dinoflagellates in the bay is dependent upon the phases of the moon. 

The best time of the month to see the glowing bioluminescence of the bays of Puerto Rico is when there’s a new moon. The new moon offers little light of its own, meaning the glow of the microorganisms will be easily visible to the naked eye. On nights when there’s a lot of light like when there’s a full moon, it’s nearly impossible to see their glow.

Tours Operating During The Peak Season

The dry season is when the bays are filled with tourists and locals alike and tour companies have their hands full with visitors wishing to see the archipelago’s famous bioluminescent bays. So, if you want to make sure that you get a tour exploring these glowing waters, book in advance so your spot is secured, otherwise most tour companies might turn you away if you try to book last time. 

So, which are some good tours to fully see Puerto Rico’s amazing glowing bays?

Bioluminescent Bay Kayaking

Do you want to visit the bio bays of Laguna Grande in Fajardo? This tour is the best option for you! It is a 2-hour long kayaking adventure that will end up becoming one of the best memories from your Puerto Rico holiday. The great part about this tour is that you can be a part of it even if you haven’t gone kayaking before because you’ll be able to learn it all while on the tour. 

In addition, it’s also wheelchair accessible and a great option for people with special needs who want to see the bioluminescent bays of Puerto Rico.

Bioluminescent Night Kayaking

The mangrove channels are rich in dinoflagellates because the mangrove provides some nutrients essential for the growth of the dinoflagellates. If you go on a tour kayaking through the mangrove channels, you’ll be sure to witness lots of awesome bioluminescence and have the time of your life. 

The best part is that you can check for availability and get instant booking confirmation online. These tours are conducted in the dark so make sure to book by checking the lunar calendar.


The best time of the year to visit Puerto Rico’s bio bays is during the dry season that extends from December to April. Make sure you book a tour early on in this peak season because most tourists want to tour the bays during this time. 

Since a bioluminescent bay is the sort of thing you only see once in a lifetime, make sure to extend a tour of them in your Puerto Rico trip!


Recent Post

Water Tours

Explore the sea with a variety of experiences such as kayaking, scuba diving, and boating!

Land Tours

Find land adventures from ziplining through the jungle treetops to exploring hidden waterfalls.

Food Tours

Get a taste of the real Puerto Rico with the top culinary and beverage tours across the island!