The best scuba-diving site off St. Thomas, especially for novices, has to be Cow and Calf Rocks, off the southeast end (45 min. from Charlotte Amalie by boat); here, you'll discover a network of coral tunnels filled with caves, reefs, and ancient boulders encrusted with coral. The Cartanser Sr., a sunken World War II cargo ship that lies in about 35 feet of water, is beautifully encrusted with coral and is home to myriad colorful resident fish. Another popular wreck dive is the Maj. General Rogers, the stripped-down hull of a former Coast Guard cutter.
Experienced divers may want to dive at exposed sheer rock pinnacles like Sail Rock and French Cap Pinnacle, which are encrusted with hard and soft corals, and are frequented by lobsters and green and hawksbill turtles. Both spots are exposed to open-ocean currents, making these very challenging dives.
Coki Beach Dive Club, Coki Beach (tel. 800/474-COKI [474-2654] or 340/775-4220; www.cokidive.com), a PADI center, offers scuba-diving courses and guided dive tours for beginners and certified divers alike. You can also rent diving and snorkeling gear here. A one-tank dive costs $65, while a two-tank dive is $85, if you use the club's equipment.
St. Thomas Diving Club, 7147 Bolongo Bay (tel. 877/538-8734 in the U.S., or 340/776-2381; www.stthomasdivingclub.com), is a full-service, PADI five-star IDC center, and the best on the island. An open-water certification course, including four scuba dives, costs $429. An advanced open-water certification course, including five dives that can be accomplished in 2 days, goes for $425. You can also enjoy local snorkeling for $55.
DIVE IN!, in the Sapphire Beach Resort and Marina, Smith Bay Road, Route 36 (tel. 866/434-8346, ext. 2144, in the U.S., or 340/777-5255; www.diveinusvi.com), is a well-recommended, complete diving center that offers some of the finest services in the U.S. Virgin Islands, including professional instruction (beginner to advanced), daily beach and boat dives, custom dive packages, snorkeling trips, and a full-service PADI dive center. An introductory resort course costs $105, with a one-tank dive going for $80 and two-tank dives costing $110. A six-dive pass costs $300.
With Homer's Scuba and Snorkel Tours (tel. 866/719-1856 or 340/774-7606; www.nightsnorkel.com), you're provided with a submersible flashlight, glow stick, and wet suit, and taken on an eerie underwater experience at night to meet the denizens of the deep. Various sea creatures such as an octopus will glide before you. The cost is $50 per person, and tours are conducted Tuesday to Saturday with reservations required.
A Thrilling Dive for Nondivers -- Virgin Islands Snuba Excursions (tel. 340/693-8063; www.visnuba.com) are ideal for beginning swimmers. These special excursions are offered both at Coral World on St. Thomas and at Trunk Bay on St. John. With Snuba's equipment -- an air line that attaches to an air tank floating on the surface -- even novices can breathe easily underwater without the use of heavy restrictive dive gear. The Snuba operations begin in waist-deep water and make a gradual descent to a depth of 20 feet. This is great fun for the whole family, as kids ages 8 and up can participate, and no snorkeling or scuba experience is needed. Most orientation and guided underwater tours take 1 1/2 hours, costing $65 per person on St. John. On St. Thomas, a pass to Coral World is included, and the rate is $68 for adults and $65 for children 8 to 12. Reservations are required.