Discovering bioluminescent bays in Puerto Rico

The Natural Reserve of Mosquito Bay provides the perfect setting for bioluminescence. The mangrove swamps feed the organisms with decaying organic matter, creating the perfect habitat.

The lack of light pollution from any nearby settlements also helps to make this one of the most clear spots to see this natural wonder in its full glory.

Mosquito Bay was recognized in 2006 by the Guinness World Records as the brightest bioluminescent bay in the world. Stay overnight in Vieques to make the most out of this once in a lifetime experience.

Book a clear-bottomed kayak trip in Mosquito Bay

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Laguna Grande is actually more of a lagoon than a bay, but that doesn’t make it any less impressive.

It’s the most popular of the three bioluminescent bays as it’s the closest to San Juan. It's part of the Cabeza de San Juan Nature Reserve in the town of Fajardo. Located about 45 minutes from San Juan or 30 minutes from the resorts in Rio Grande.

Tours are often combined with El Yunque National Forest, a great way to save money on your trip to Puerto Rico. But day tours can get busy and are best booked in advance.

Book a kayak tour through the mangrove forest and see the glowing waters as you get closer to the lagoon.

La Parguera is located in Lajas at the southwestern corner of Puerto Rico. Known by locals as the “Phosphorescent Bay”, it's much quieter than the other options as you will need to do a day trip or stay in the area overnight to visit.

The major benefit to visiting the bioluminescence at La Parguera is that tours are a lot less crowded. Tours are also cheaper in Lajas than the more famous Mosquito Bay.

La Parguera is the only one of the bioluminescent bays where swimming is allowed. Motorboats can come in and out so take care if swimming here.

Visit: Take a tour from San Juan.

• Book a tour and call a day or two in advance to confirm that the bay's brightness has been above 30% in the days before.

• Visit in dry weather (most likely December-April), when there is little or no moonlight. Even sea temperatures can have an effect on the brightness levels and it’s best to choose the optimal time to avoid disappointment.

• To keep this spectacle alive for future generations, try to avoid using hand creams, sun spray, bug repellent, and any other lotions that can harm the organisms.

Most tours of the bioluminescent bays are by kayak or boat. La Parguera is the only bio bay in Puerto Rico where swimming is allowed.

Kayaking

Whilst kayaking offers a more interactive and peaceful experience, boat tours are better suited to families and the less mobile.

Kayak tours cost anywhere between $45 and $60 for around 2 hours, they run at sunset (usually around 7:30pm).

Boat tours

Electric boat tours in La Fajardo cost $52 and last 1hr 15, whereas in La Parguera bigger boats cost $12 for around 2 hours.

You can also take glass bottom boats here to see the ocean glow without even getting your feet wet.

The best time of year to see the bioluminescent bays in Puerto Rico is during the dry season from December to April.

The rainy season, from June to November, can disrupt the water with heavy rainfall making it hard to see the blue-green glow.

The weather in Puerto Rico is perfect in the dry season but it can get busy. Avoid mid-March if possible, which is when a lot of families with children and college students travel for Spring Break. This makes the bays pretty busy and prices are at a premium.

The lunar cycle also has an effect on the visibility, if you visit during a new moon the bays will appear much brighter due to the darker skies.

The type of bioluminescence you can see in these bays is caused by millions of microscopic organisms called dinoflagellates.

Similar to fireflies, these creatures emit a blue-green light when stirred by movement.

They are found just about everywhere in the ocean, but it’s only when they gather in huge numbers that you can see the starry glow that can be seen in abundance here in Puerto Rico.