There's plenty to do on St. Croix...
Diving: St Croix is almost completely surrounded by a barrier reef, and the largest living reef in the Caribbean. There are over 50 moored diving sites, including the famous wall that runs along the north shore; the wall, beginning at 30' drops to over 13,000', making it the steepest in the world. Long over-looked as a dive spot, St. Croix offers more diversity than any of the other islands.
Eco tours: Kayak at Salt River National Park and Ecological Preserve, take a tour, and observe the rich marine life; hike or snorkel the island's nooks, explore! Learn about the ecosystem and its impact. There are several turtle nesting areas, monitored by the St. Croix Environmental Association, which offers educational tours at various times.
Island tours: To really see the island, try an island tour in an open air jeep. There's something for everyone-- going through the rain forest, visting historical ruins, swimming in the tide pools, horseback riding along the beach or through the rain forests.
Fishing: The warm waters are home to marlin, wahoo, yellow-fin tuna, king fish and dolphin(fish). Charters are available in half or full days.
Snorkeling, windsurfing & water sports: If diving's not your thing, you can still see the gorgeous coral reefs and marine life from the surface. The waters, waves & breezes offer many forms of watersports at the many beautiful beaches.
Buck Island: Just 1 1/2 miles northeast of Christiansted, Buck Island is a must to visit. It is one of only three Underwater National Monuments in the U.S. Accessible only by boat, it offers tours, history, lagoons, and a spectacular underwater trail. A trip to Buck Island is a must!
And more...Island-hopping, the Ironman (featured on ESPN) , restaurants, culture, two 18-hole golf courses, the St. George Botannical Gardens, and of course, relaxing on the beach.