Originally discovered by a pair of Bermudian boys trying to retrieve a lost ball in 1907, this network of subterranean lakes, caves, and caverns houses translucent formations of stalagmites and stalactites. All tours are guided, and lead down steep stairwells carved into the rock and across a floating pontoon bridge that spans 55-foot-deep crystal clear subterranean lake. Using the lighting system, the guides make shadow puppets on walls covered in thick calcite mineral deposits, and are fond of pointing out the similarity to the skyline of Manhattan. Note: If you suffer claustrophobia, you may want to skip this one, as some passages are quite tight.