A Glow in the Dark Sea Bio-luminescence in Puerto Rico

By: Shelley Seale
Aerial view of the coastline of Vieques National Wildlife Refuge on Viques, an island in Puerto Rico. Getty Images / Image is the copyright of Jonathan Reid and may not be used without the permission of the artist.

I am sitting in a tiny airport in Puerto Rico, called Ceiba, awaiting what is to be the shortest flight of my life. The gate agents have recorded all of our weight– from checked luggage to carry-on bags and even our persons – for the small charter plane that will take us over to Vieques Island.

The door to the tarmac opens and a woman sticks her head in, beginning to call out by last name the shortlist of passengers for our flight. Guess that’s our boarding call.


Flying to the island of Vieques from mainland Puerto Rico (of course, itself an island) doesn’t take very long; in fact, blink and you just about miss it. The props start turning, we lift off the runway strip, and barely have enough time to get up in the air before we are starting the descent. When I’m back on the ground on Vieques Island, seven minutes have passed since taking off.

La Isla de Vieques is like nowhere else in the Caribbean. Most of its land remains undeveloped; it was here that the U.S. Navy used, and abused, 60 percent of the island for sixty years as a training site. In 2003 the Navy left Vieques and passed control back to the Department of the Interior – who had to remove explosives and military waste to the tune of more than $200 million.

Aerial view of the coastline of Vieques National Wildlife Refuge on Viques, an island in Puerto Rico.
Getty Images / Image is the copyright of Jonathan Reid and may not be used without the permission of the artist.

The Navy’s occupation of Vieques was controversial at best; in 1999 Puerto Rico Governor Pedro Rosello said, “Never again shall we tolerate abuse of a magnitude and scope the likes of which no community in any of the fifty states would ever be asked to tolerate.”

That was then; this is now. Today the Navy land is under the Fish and Wildlife Administration, making the island the largest national refuge in the Caribbean. Wild horses roam around freely; the beaches are pristine and undeveloped, surrounded by native flora instead of concrete. There are no McDonald’s, no kitschy souvenir stands. Vieques was voted the best Caribbean island by Travel + Leisure, and made Conde Nast Traveler’s 2011 Hot List.

And Vieques Island is home to the reason we have come: the brightest bioluminescent bay in the world. The bio-bay creates a sea that glows in the dark; there are five such places in the world and three of them are in Puerto Rico. The largest, and most filled with bioluminescence, is Mosquito Bay here on Vieques. A microscopic organism from the Dinoflagellata family lives in these waters, and bioluminescence is its natural defense system.

When the tiny creatures are disturbed, they give off a chemical reaction that produces light. This attracts bigger water predators, who feed on the creatures who were planning on eating the dinoflagellate. And for those of us witnessing this phenomenon, it creates a magical, light-filled show that looks like blue fireworks underwater.

We go out on Mosquito Bay after sunset with Island Adventures, a highly-recommended operator of excursions to the bay. After a bus ride down the bumpiest dirt road imaginable, trees scraping along the sides and top of the bus with every lurch, we arrive at the water’s edge to board an electric pontoon boat. This boat will take us silently through the water to witness the bio-luminescent marvel at work.

As the boat moves through the bay, fish dart away from it. As they swim and even jump through the water, they leave a wake of brightly glowing contrails behind. It really is quite spectacular. We are allowed to put our feet in the water and the splashing creates more glowing droplets. The Island Adventure biologist guides pull buckets of the water up onto the boat for us to examine and play with, but people are not allowed to get into the water. Sunscreen, perfumes, shampoo, deodorant, and other things we use are very dangerous to the bay and our little dinoflagellate friends.

I learn that although the microscopic creatures are present in all the ocean and seawater of the world, typically they are at a volume of 30-50 per gallon of water. Here in Mosquito Bay, there are more than 700,000 of them per gallon, creating this rare and endangered natural wonder.

I recommend that you don’t come to Puerto Rico without visiting this magical place yourself. Contact Island Adventures for a tour, and stay in style at the new W Retreat & Spa. The W has a comfortable island sanctuary vibe, with the luxury and exquisite food that you’ve come to expect from W – and some of the most spectacular sunsets it’s possible to witness in the Caribbean. To get to Vieques, take the Vieques Air Link; there is also a ferry for around $4, though it sometimes runs erratically.