In pitch-black night, I dive into one of Puerto Rico’s bioluminescent bays, where the seemingly magical waters glow in the dark
Our boat comes to a full stop, drops the anchor and turns off all the lights, one by one, enveloping us in the silent darkness. My eyes take a few minutes to get used to the sudden void. We are about a mile away from the mainland, but there are no sources of light whatsoever, save for the rising moon and a few stars peeking through a haze of the evening clouds.
“We’ve got really good conditions tonight,” says our boatman, Captain Cachi of Paradise Scuba & Snorkeling. “The less light, the better. Now, let’s put your swimming gear on.”
Still adjusting to the blackness, I fumble to put on my snorkelling mask and fins, and then feel my way to the back of the motorboat. Before I walk down the steps, I pause, suddenly feeling goosebumps all over, despite the tropical heat.
It’s both thrilling and a little scary to jump into the dark, endless currents of La Parguera Bay, a vast stretch of ocean off the coast of Puerto Rico. It is one thing to snorkel here during the day, splashing in the greenish-blue waves and peeking at the colourful coral and lively fish. But doing so at night, when you can’t even see where the air ends and the waves begin, is a different experience altogether.
At night, the ocean seems endless and bottomless and a little intimidating. But that’s the whole point of the trip. Once in the water, I will create light myself. Well, not entirely. In fact, trillions of tiny oceanic creatures will help.
I shake off my hesitation, waddle down the steps and take a plunge. At first, nothing seems to happen — everything is as murky and opaque as before. “Start swimming,” Captain Cachi instructs me from the boat. “Start paddling, kicking, moving around.”
Facedown in the waves, I follow his advice — and suddenly the water around me floods with light, just as he promised. The harder I paddle, the brighter it glows. In this mystic radiance, I feel like a magical creature myself, a mermaid painting the ocean in golden graffiti. Or setting off underwater fireworks. Or bathing in cool, liquid gold. It is surreal and otherworldly, a unique natural phenomenon.
Called bioluminescence, this glow comes from a myriad tiny, single-celled marine algae. They contain a protein called luciferin, which can react with oxygen molecules present in the water, generating light. “It is a cold reaction,” marine biologist Sandra Schleier of Pure Adventure explained to me later. “It doesn’t produce heat. It only emits light.” When I agitate the water by paddling, the luciferin and oxygen intermix a lot, causing the shimmering streaks that resemble the New Year’s confetti.
This particular non-toxic algae can be found in different parts of the Atlantic, but there are some spots it loves more than others: lagoons where the currents aren’t strong, water is very warm, and there are islands with mangrove forests nearby, which in heavy rains release nutrients into the water. When these conditions occur together, the algae thrive and grow in large numbers.
Our boat is docked in a shallow lagoon right next to a small mangrove-covered island, so the water is warm and calm, and the food is aplenty. All of that makes the algae very happy and they multiply profusely. They twinkle and sparkle and flicker with my every move, as I paint the water in different shapes and patterns. When I splash, I set off bursts of sparks.
When I circle my arms, I create serpentine weaves. And when I paddle with my fins, I kick off a golden avalanche like a launching rocket. Because it’s so dark, cameras can’t adequately capture the spectacle. It’s not a phenomenon to photograph but to experience.
The bioluminescent phenomenon occurs in only a handful of places in the world, including the Maldives, Bali, Jamaica and even parts of Florida. Three of these unique bays are in Puerto Rico, and La Parguera is the only one you can swim in. The other two — Laguna Grande near the town of Fajardo and Mosquito Bay at Vieques island, seven miles off Puerto Rico’s mainland — are open for kayaking tours only. Watching the glow bloom underneath the silently gliding kayaks is a wondrous sight, but nothing beats swimming in cool liquid gold.
There are ecological reasons for these rules, explains Schleier. Laguna Grande and Mosquito Bay are close to the touristy areas, with heavy traffic and many visitors. The skin lotions and bug sprays that people inevitably wear contain chemicals that wash into the water and damage the delicate ecosystems of these bays. So the busier places must use strict policies.
But La Parguera is still off the tourist track. It’s a two-hour drive from San Juan, Puerto Rico’s capital, and most travellers who come to this vibrant tropical island never venture far from the city, staying in beachfront hotels. At least for now, La Parguera remains more of a local gem. You can’t get to this bioluminescent bay on kayaks — instead small boats take people here to swim.
Spinning and swirling, I lose track of time, and then suddenly hear Captain Cachi’s call — all aboard! The magic ends as I abruptly lose my mermaid powers. The last sparks die the moment I climb up the steps. As the boat stirs back to life, I look at the once again darkened lagoon and make a wish to come back here again — and soon.
I feel incredibly lucky to have experienced this unique phenomenon while it is still ecologically sustainable, because if La Parguera turns into a hot tourist spot, it may become off-limits, too. But for the time being, those willing to take a whirlwind drive through little towns, empty beaches and meandering rainforest paths can take a swim in the sea of light they create themselves.
Writer Lina Zeldovich travelled as a guest of Discover Puerto Rico, which did not review or approve this article. Travellers are reminded to check on public health restrictions that could affect their plans.