Fajardo

The water in Mosquito Bay sparkles like stars when disturbed due to the hundreds of thousands of bioluminescent dinoflagellates resident there. Of the bioluminescent bays all over the world, Vieques' Puerto Mosquito has been certified the brightest by the Guinness Book of World Records.A trip to Bio Bay, as it's locally known, is one of the best tourist attractions in Puerto Rico and well worth the excursion from San Juan. Several tour companies offer kayaking and snorkelling in the magical water, often ranked as one of the most romantic places on earth. The bioluminescence is at its brightest during the full or near-full moon, and this is considered the best time to visit.

Dubbed 'the enchanted isles', Vieques and her smaller sister Culebra are located off Puerto Rico's east coast, accessible from San Juan by air and from Fajardo by ferry. Both support a few thousand friendly, laidback inhabitants who live life peacefully and slowly, enriching rather than impacting on the natural beauty of their environment.Vieques is 20-odd miles long and five miles wide, and consists largely of the biggest wildlife sanctuary in the Caribbean, protected by the United States Fish & Wildlife Service. Some of the world's most beautiful beaches, with azure clear waters and sugary white sand, are to be found in the sanctuary.Visitors planning to see Vieques should consider staying overnight to experience its premier attraction, Bio Bay. On a moonless night, the bay glows with the bioluminescence radiated by microscopic one-celled organisms called dinoflagellates, providing an unforgettable sight.Smaller Culebra, just seven miles long and three miles wide, is a few miles north of Vieques and is renowned for the clarity of the waters washing its shores. This is caused by the fact that the island has no rivers or streams causing run-off: the arid island has to have water piped from Puerto Rico via Vieques.This quiet, unspoiled island offers unrivalled snorkelling and scuba diving in its magnificent encircling reefs, as well as kayak expeditions and hiking trails for bird-watchers through the Culebra National Wildlife Refuge.

Located on three promontories on the extreme northeast corner of the island, Las Cabezas reserve is one of the most beautiful and bio-diverse natural areas in Puerto Rico. The reserve is close to Fajardo, a major marina and diving resort, located about an hour's drive from San Juan. The area offers pristine beaches ideal for snorkelling.The reserve contains seven different ecological systems, including coral reefs, sandy beaches, lagoons, mangroves, and dry forest. It is also home to several endangered species. Boardwalk trails provide easy access to the different natural sites. A restored 19th-century lighthouse, El Faro, is situated on one of the headlands and offers an information centre and observation deck.