One of the world's best snorkeling spots is in the Bahamas. The tiny Bimini Islands offer a great variety of snorkeling sights, including coral gardens, plenty of reef fish, and (maybe) even the road to the legendary lost city of Atlantis, a mysterious formation of two parallel lines of rectangular rocks in 15 feet of water. One of the best known sites is the wreck of the 282-foot concrete ship Sapona, driven up on a reef just south of North Bimini during a 1926 hurricane. The hull lies partly submerged in 20 feet of water. Lucky snorkelers may meet up with a pod of spotted dolphins.

Part of the appeal of Culebra is the sheer economy of getting there. From the main island of Puerto Rico, hop on a ferry for a mere $2.25. From the landing at Dewey, the only town on the island, hop on the bus for $2 to reach Playa Flamenco. The beach is popular for parties and camping, but you can leave everyone behind with a 20-minute walk across this desert island to Carlos Rosario Beach, one of the great snorkeling spots in the Caribbean.

Snorkelers can find great adventures throughout the Turks and Caicos. But Salt Cay has some special attractions. Dive tour operators lead expeditions to forests of elk horn coral with resident nurse sharks and sting rays. Uninhabited cays nearby offer pristine fish viewing. The British frigate HMS Endymion, wrecked on a coral reef in 1790, lies in only 20 feet of water. Winter offers a special bonus, when snorkelers may be able to swim amidst the looming shapes of humpback whales singing their eerie songs.

St. John's crenulated coast is rich with protected places to snorkel. Since practically the entire island is a national park, there's not much of the sediment-filled runoff that has damaged coral and clouded the water at some other Caribbean locations. Beginners may like to start at Trunk Bay, where signs along an underwater "trail" point out highlights. More experienced divers will want to search out more natural sites. Some, such as Leinster Bay and Haulover Bay, are accessible from shore. Others require a boat ride.

One of the best snorkeling sites in the Hawaiian Islands is the very accessible Makaha Beach Park, located on the leeward side of Oahu. Visibility runs 100 feet or more. Whether snorkeling at the park beach or at some of the outlying reefs, you'll spot plenty of fish, sponges, and corals, with a chance to see spotted eagle rays, green sea turtles (which grow up to 400 pounds), and resident spinner dolphins. (Beware that in winter, surf may prevent swimming.)

Diversity is the draw at Bunaken National Marine Park in North Sulawesi, part of the Indonesian archipelago. Founded in 1991 to protect the extensive and undamaged coral reefs, the park is 97 percent water. It has unrivaled biodiversity, with huge varieties of corals, invertebrates and more than 2,500 species of fish. The park and nearby communities have worked hard in recent years to protect resources while helping local villages benefit from tourism.

As you plunge below the surface, the sounds of whales fill your ears. The shadow of a 40-ton adult humpback comes into view beneath you. Then you notice its two-ton calf. Every year between August and November, humpbacks migrating north from Antarctica rest in the waters of the Australes Archipelago. If you're lucky, you can look literally eye-to-eye with a barnacle-encrusted creature more than 40 feet long.

The Great Barrier Reef lies 12 to 50 miles off the northeastern shore of Australia. The amalgam of 2,500 reefs stretches 1,400 miles, covering an area as large as California. Many companies run day trips to the reef. Otherwise, Green, Heron and Lady Elliot Islands have good diving right from the beach. The vast shallows are inhabited by spotted eagle rays, manta rays, green sea turtles, spectacular nudibranchs, and hundreds of species of corals, reef fish and mollusks.

Fiji's 330 islands are a snorkelers' paradise. A spectacular feature of the archipelago's reefs are "bommies," pillars of coral that rise from the depths to within a few feet of the surface. On the broad bommie top live giant clams, starfish, urchins, anemonies, and a variety of fish, including clownfish, plumed lion fish, groupers, puffers, wrasses, barracudas, manta rays, and reef sharks. Boat tours visit far-flung reefs, though some good ones are accessible from shore.

Not many freshwater swimming holes can compete with salt when it comes to water clarity. That's not the case with the crystal-clear spring-fed basins of central Florida. Many have outstanding opportunities to view fish and other creatures, including half-ton manatees and the occasional alligator. One good spot is Silver Glen Springs in Ocala National Forest. Water fills the basin through a deep funnel-shaped cavern. Snorkelers spot sunfish, largemouth bass, tilapia, armored catfish, and whirling schools of mullet. Another good bet: Blue Spring State Park, where swimming is allowed in the pool and outflowing stream only when manatees aren't present. Drift in the current among schools of three-foot-long gar.