"Ambergris Caye, in Belize, made this year's rankings at No. 2. The long, narrow barrier island is known as the place to see the Great Blue Hole — a 406-foot-deep, 1,000-foot-wide marine sinkhole that looks like an enormous blue circle that can be seen from space. Scientists predict it won't be around forever, so diving enthusiasts would do well to visit sooner rather than later." - Travel + Leisure Editors