Swim with sharks!

— -- The shark is lying languorously in the arms of your snorkeling guide, who holds it like a cat, while you are petting it. Except that it's four feet long. The skin feels like rubber covered with a layer of sandpaper. It is a rich reddish brown, but lighter on the belly, which is where the shark seems to enjoy being scratched.

The shark makes no move to resist, but when the guide releases it, it lazily flicks its tail—just once—and gently disappears into the very blue waters of Shark Ray Alley in Belize's Hol Chan Marine Reserve, just off Ambergris Caye. All the dive shops in Ambergris Caye run snorkeling trips here, but the guide from Tranquility Bay Resort (which specializes in diving and fishing trips), seems especially adept at catching sharks by their fins. He also has a sense of humor: To make the generally recognized diver's sign for "look, there's a shark," he puts his hand perpendicularly against his forehead. To tell us that it's a nurse shark, he pretends to grab his non-existent breasts.

Say the word "shark," and a thousand bloody images come to mind: Jaws, of course, as well as rare but memorable news stories from Australia, California, Florida, and South Africa, where great whites sometimes mistake a human for a seal with deadly and newsworthy results. (To put this in perspective: The International Shark Attack File estimates that for every human killed by a shark, 10 million sharks are killed by humans.)

Most sharks, however, are just fish that eat other fish ... or seals or walruses. Or, with some species, plankton and krill. They range from tiny sand sharks all the way up to the whale shark, which at 50 feet in length, is the largest fish in the sea.

Swimming with the giant whale sharks is gaining in popularity, in part because these spotted behemoths have predictable migration patterns, so tour operators can reliably find them. And they are relatively safe to swim with because they feed on microscopic plankton, krill, and algae. Whale sharks are found in oceans worldwide; in the Americas they migrate near the Yucatan peninsula every August, where they are called "dominos" in reference to their spots. Operators in Mexico and Belize offer trips where divers can swim with these gentle giants.