Buck Island Reef National Monument protects one of the finest elkhorn coral barrier reefs in the Caribbean, lying about a mile and a half off St. Croix's northeast shore. The reef is the main attraction: a sweeping arc of elkhorn coral that rises to within a few feet of the surface and shelters a vivid community of reef fish, sea turtles, rays, and the occasional nurse shark resting on the sandy bottom. The underwater snorkel trail runs through the clearest section of the reef, and the water here is typically calm enough for swimmers of any ability.
Day trips to Buck Island depart from Christiansted's King's Wharf, and the crossing takes about 30 to 45 minutes depending on the boat. Several licensed concessionaires run half-day and full-day trips; most include snorkel gear, a short naturalist briefing, and time on the island's own beach, where hawksbill turtles nest from June through October. The island itself is off-limits except on the designated trail, but the beach on the southwestern shore is public and lovely. This is one of the most rewarding half-days in the entire US Virgin Islands.