Neptune Memorial Reef, Florida
Despite its appearance, the Neptune Memorial Reef isn’t a lost or abandoned underwater city. This area is located east of Key Biscayne in Miami, Florida. Neptune Memorial Reef was designed by artist Kim Brandell and opened to the public in 2007. The structures are located 40 meters underwater, and the area is considered to be the largest man-made reef in the world! There are dozens of interesting structures to take in and explore throughout the reef. It’s become a popular tourist destination and a thriving marine habitat.