Vieques sports two of few bioluminescent bays in the world. If there is one thing you must do while in Vieques is visit the bio-bay of Puerto Mosquito. The experience is incredible!
Imagine diving from the deck of a boat on a moonless night into the dark and serene Caribbean waters. You see the water splash up in a burst of millions of lights like fireworks from undersea. As you move through the water you glow like a diving angel, and when you resurface, thousands of sparkling lights remain on you, if only for a brief moment, as if you were part of the magic. This natural wonder is still around for your enjoyment. Tours are available by kayak or electric boats.
Once in Vieques you will also want to visit the museum at the Lighthouse and the one at the Fort Conde De Mirasol.
So that you do not experience cultural shock, this is a summary of what you will and will not see in Vieques. You will see loose farm animals crossing the roads, they could be chicken, cows or horses. You will hear the singing of roosters at dawn. You will not see any traffic lights, Mc Donald's, or T-shirt-shop-laden-street. Expect the driver in front to stop at any minute to greet the driver on the opposite lane. And expect the sun to be out, it does not rain much in Vieques and when it does the sun usually prevails.