The world’s second-largest barrier reef stretches 185 miles along the Belizean coast, from the northern tip of Ambergris Caye (a 20-minute plane ride from Belize City) to Sapodilla Cayes in the south. Throughout these diverse waters, divers and snorkelers are wowed again and again by fish and marine life. Among the 500 resident species, keep an eye out for nurse and reef sharks, hawksbill and loggerhead turtles, parrotfish, and endangered elkhorn and staghorn coral—plus the only-in-Belize whitespotted toadfish. The reef’s most spectacular diving site is the Great Blue Hole, a perfectly round, 1,000-foot-wide, 450-foot-deep sinkhole. It’s Belize’s most cinematic aquatic attraction, made famous by oceanographer Jacques Cousteau.