Bio Bay...

"Hidden along the Caribbean coast is one of the most spectacular Bioluminescent Bays in the world. The mysterious blue-green light is created by micro-organisms which thrive in an environment uniquely suited to their needs. A trip into the bay on a balmy night is a magical experience. Fish flash by in dark water, and a swim is like floating through stardust." - Captain Sharon Grasso

Island Adventures Biobay Tours offers nightly excursions aboard our electrically powered double-pontoon boat through the amazing waters of Puerto Mosquito in Vieques Island. Our bilingual guides explain the fragile ecology of the plants and animals of the bay, give interpretive star lectures, and then park the boat in an area of high bioluminescent concentration, giving visitors the chance to swim with the millions of glowing creatures.

Why does the water glow?
This unique bay contains up to 720,000 single-celled bioluminescent dinoflagellates per gallon of water. These half-plant, half-animal organisms emit a flash of bluish light when agitated at night. The high concentration of these creatures (Pyrodimium bahamense) can create enough light to read a book from. Learn more by reading several articles on the bay.

To read more about it... go here.

In need of a free drink?

Why don't you check out Casa Bacardi.

There is no admission for the factory itself. They give you 2 drink coupons each for a bicardi drink of your chioce or drink the reserve straight. On the tour see the history and see some hands on or smells on exhibits;) During the tour, they allow you to send a video message to anyone. Take email addresses to send a video message After the tour, they drop you off at the gift shop. You might want to buy some of the very special limited release 12 year old they sell only at the factory. You can either take the spanish or english tour.

Directions: To get to Bacardi from old San Juan, you just go to Pier # 2 and take the ferry. The ferry from downtown San Juan is 50 cents pp, per way. There is a fee for the shuttle bus from the ferry to the factory

Source

Or this:

IF YOU MUST GO TO BACARDI, KNOW THIS: Bacardi tour: PROS: free tour, complimentary beverages (2 per person), inexpensive alcohol and gifts, gracious staff CONS: 4+ hours total (including travel from Condado), BORING tour, bus/taxi to ferry to bus/taxi just to get there and back, surrounded by other tourists, long lines for drinks and/or gift shop GREAT ALTERNATIVE TO THE ABOVE!!! Don Q Rum has a "Casa Don Q" across from Pier 2 in Old San Juan. Think of it as a miniture Casa Bacardi tour, and at your own pace. Same free beverages, excellent gifts, gracious hosts, and interesting facts as Bacardi (and I, personally, think better rum!) without the extra ferry and bus/taxi ride. SUGGESTION: when you first walk in, go directly to the bar area and ask for a "house mix" (very tasty) with an extra shot of Don Q Crystal and take your time browsing the company/manufacturing info in the clean, air-conditioned Casa Don Q.

# Address: Old San Juan, across from Pier 2.
# Directions: Once you're in Old San Juan, look for Pier #2, stand in front of it, and turn around 180 degrees.