East of Puerto Rico on Vieques Island, the snorkeling at Playa De La Chiva is known for its diverse and plentiful marine life. Also known as Blue Beach, the main snorkeling attraction is Isla Chiva (aka Chicken Island) in the center of this mile wide bay. While the eastern edge of the bay has some crevices and canyons, the snorkelers at Playa De La Chiva come to explore Isla Chiva. Most snorkelers swim from the east side of the island to the west, and if the waters are calm, you can try to circumnavigate the island (0.75 miles).
Alternately, try Cayo Real just off Esperanza Pier. This is an easy shore access dive in shallow waters up to 30 feet deep. There are sea grass beds to explore and you can snorkel out to the small island of Cayo Real.
For another oddity to explore at dusk, check out Bioluminescent Bay near the City of Vieques which is filled with bioluminescent dinoflagellates.
To reach Puerto Rico by air, fly into Luis Munoz Marin International Airport (SJU). There is a four-times-a-day ferry service from Fajardo to Vieques Island.
Overall, Vieques Island is the 5th most popular snorkel dive spot of all 17 snorkeling dives in Puerto Rico.