Two of the most common underwater endeavors are snorkeling and scuba diving. Snorkeling requires minimal equipment and instruction: $50 will buy you a mask, snorkel and set of flippers, or you can rent gear from the nearest surf shop. Scuba diving takes a little more training. You'll need to earn your PADI (Professional Association of Diving Instructors) certification card before you can get started.
You'll find one of the world's best snorkel experiences in Rurutu, Tahiti. Every year, between August and November, humpback whales pass through the warm, shallow waters of Ruruta to mate and give birth. Snorkelers lucky enough to witness these massive mammals can dip their heads underwater and hear the gorgeous, eerie song of the whales before the gentle creatures swim into view. For snorkelers who want to stick closer to home, the Florida Keys offer some of the best domestic snorkeling in the United States.
From wreck diving to night exploration, scuba diving destinations abound. We recommend the Grenada locations, such as Molinere Underwater Park, which contains Jason deCaires Taylor's underwater sculptures. Not only are these works visually stunning, they also serve as artificial reefs, offering divers a way to explore reef ecology without unwittingly damaging the fragile ecosystems of natural barrier reefs.
Divers who want to take their diving to the next level might consider trying their fins at one of the world's most dangerous sports. We talk about cave diving in the next section.