As lovely as the Caribbean is above the water, beneath the waves it is a treasure trove for divers and snorkelers of all ability levels, with mysterious sunken ships, long-forgotten wrecks, colorful coral and exotic sea creatures. Read on to discover the best Caribbean snorkeling and diving sites.

The Cayman Islands

Three outstanding dive options in the Cayman Islands are Stingray City, where you can feed and pet stingrays; Shark Alley, the most common place on the islands to see sharks; and Bloody Bay Marine Park, which comprises 22 of the islands' dive sites and has two walls, Bloody Bay in the west, Jackson in the east. The reef here starts at an easy 6 feet deep, but soon plummets to an awesome 1,600 feet below the surface. In contrast, Stingray City is shallow enough to make it an excellent option for snorkelers as well as divers.

Bonaire

Bonaire's entire coastline, even the small neighboring island of Klein Bonaire, is preserved as a marine sanctuary down to 200 feet below the surface. As you snorkel or dive, you'll want to keep an eye out for the elkhorn and staghorn coral as well as for colorful tropical fish. This fragile ecosystem has been under protected status for 25 years, and any diver wishing to explore these waters must take part in an orientation session covering the park's rules and regulations.

Saba

Small, volcanic Saba has a marine park that, like Bonaire's, takes in the entire coastline of the island. Here, you'll want to see the Pinnacles, peaks of underwater mountains that start around 85 feet below the water's surface and plunge into the depths.

The British Virgin Islands

At the Baths, snorkelers can navigate a striking landscape of enormous boulders and glimpse exotic sea creatures darting among the grottoes and tranquil pools. The wreck of the Rhone, a mail ship that sank in 1867, is an evocative dive site off Salt Island, and a good destination for experienced divers.

Turks and Caicos

Surrounded by one of the largest coral reef systems in the world -- 65 miles across and 200 miles long -- with visibility up to 200 feet, these islands are consistently listed among the top dive spots in the world. Top sights include the HMS Endymion, which sank in 1790, and drop-off diving near Grand Turk, where the sea walls descend into unexplored blue holes almost 7,000 feet below sea level. On the way down, you'll pass black coral, purple sponges, and thousands of playful fish.

The U.S. Virgin Islands
Snorkelers should head to Buck Island's underwater snorkeling trails off the northeast coast of St. Croix. This 704-acre underwater national park boasts clear water and a treasure trove of coral reefs. Trunk Bay on St. John has a 650-foot-long underwater snorkeling trail that is, believe it or not, marked with signs to help you identify what you're seeing, whether it be coral, sea fans or anemones. This is a great option for older kids.
From Margot Weiss, for About.com

Photo Courtesy of Turks and Caicos Tourist Board