In Puerto Rico, Underwater Fireworks by Washington Post
By Gary Lee The Washington Post Sunday, January 10, 1999; Page E02

As I drifted in a small boat across a quiet cove off the coast of Puerto Rico, the wind seemed to howl a bit louder and the waves started flapping against the bow. Despite the ominous mood, however, I was not fully prepared for the jolt I would get after splashing into the water. Bobbing to the surface, I took a look at my hands, arms and legs and let go a howl. They glowed.

My entire body had turned a luminescent yellow-green, like the Day-Glo necklaces kids wear on summer nights. When my fellow travelers jumped from the boat, they, too, lit up, one by one. And as I began regaining my composure, I noticed that the fish whizzing by and everything else that moved through the waters had turned the same glistening goldish-emerald hue. The water underneath me was lit up like a miniature underwater fireworks display.

We were in Mosquito Bay, arguably the most magnificent of the few bioluminescent bays left in the world.

The phenomenon of bioluminescence is caused by millions of dinoflagellates--single-cell organisms that emit a glow and call Mosquito Bay home. Harmless to humans, dinoflagellates can be found in heavy concentration in waters the world over--including the Chesapeake Bay, according to Sharon Grasso, our tour guide. But what attracted such an unusually heavy preponderance of them to Mosquito, a bay off the shores of Vieques, an island located a short hop by plane from San Juan, Puerto Rico?

TThe most likely explanations are the concentration of mangrove trees and the limited access of the water between the bay to the ocean, Grasso said. The combination of food from the mangrove roots and the saline content brought about by the mixture of sea and fresh water make a perfect dinoflagellate breeding ground, she explained.

The population of the organisms is so strong in Mosquito that they cover everything in the water, including the small boat loads of tourists that Island Adventures, a small ecotourism company run by Grasso, bring to the bay every evening.

Bioluminescence enthusiasts encourage the curious to schedule a visit soon. A sports complex under construction at one end of the bay may alter the conditions of the area and kill off the dinoflagellates, they fear.

Among Caribbean travel destinations, Vieques is a well-kept secret. Ruled from the 1500s by Spain, it retains a Spanish flair, enhanced by the ruins of a fortress and other remnants of colonial power. There are secluded beaches, popular little eateries and a good sprinkling of guest houses.

But for me, no Vieques hangout could beat an evening splashing about in Mosquito Bay. Source