Tours of the bay run all year, but moonlight has a huge impact on bioluminescence – it’s crucial to avoid full moon cycles, when it’s impossible to appreciate the effect. Though most operators don’t run tours when the moon is full, they tend to play down its impact. Another problem is jellyfish, which collect in the bay and sometimes sting hapless swimmers. Again, tour operators are reluctant to make too much of this, though to be fair, the stings are rarely serious, affect only a handful of visitors and are easily treated with vinegar spray.
Conservation-minded Island Adventures (t787/741-0720, wwww.biobay.com) is the best operator and has a useful moon calendar on its website. Tours begin at their office, west of Esperanza on PR-996 (near Inn on the Blue Horizon), with an informative talk, followed by a rickety bus ride to the waterside. From here one of their expert guides takes a boat around the bay (around 1hr), stopping for at least twenty minutes for a swim and pointing out all the major stars and planets along the way, with plenty of local history and botany thrown in. They have a café (daily 5.30–11pm) at the office serving Puerto Rican and Mexican food and plenty of parking.
Abe’s Snorkelling Tours (t787/741-2134, wwww.abessnorkeling.com) in Esperanza organizes daily kayak trips to the bay at 2pm, paddling through the mangroves for just over an hour, followed by snorkelling and a beach visit, before returning to the bio bay after dark ($100). They also do night trips around the bay only (with swimming; 1hr 30min; $30). Blue Caribe Kayaks (t 787/741-2522), at c/Flamboyán 149 in Esperanza, also organizes kayaking trips for $30 per person. Vieques Adventures (t787/692-9162, wwww.viequesadventures.com) offers unique tours in their clear polycarbonate canoes for $50.