Once you've made your way offshore and the sprawling cityscape is but a distant backdrop, it's time to drop over the side and find yourself immersed in the surreal. Neptune Memorial Reef, located about three miles off Key Biscayne, is among the largest man-made reef projects anywhere. Planned to ultimately span 16 acres of the ocean floor, it also happens to be a cemetery underwater. It was designed to have the futuristic look of Atlantis, and while it's tough to say whether designers succeeded, it's definitely unique. There's an eerie calmness to it all, much as an old cemetery on land might have, except that the statues and ornamentation seem all the more otherworldly 40 feet underwater. This is particularly true when the fish get curious about your visit.