Home to the largest barrier reef outside of Australia (185 miles!), Belize has many opportunities to get up close and personal with eels, rays, and all kinds of brightly-colored fish. There are hundreds of cayes and atolls that dot the Caribbean coastline, filled with colorful coral sunken beneath the turquoise waters. Some of the best options for divers and snorkelers are found off of Ambergris Caye, including the Hol Chan Marine Reserve and the self-explanatory shark-ray alley teeming with nurse sharks happy to let you live out your swimming-with-the-sharks fantasies