Most people visiting Eleuthera never know this cave exists, which seems like a real shame. Hidden off Queen's Highway near the Hatchet Bay silos, it's the largest cave system on the island and one of the more genuinely weird and wonderful things you can do in the Bahamas. A descent down a set of rough stairs puts you in the first chamber, where natural light still filters in and a few stalactites and stalagmites give you a preview of what's ahead. Keep going and things get considerably more dramatic. The cave runs about a mile underground across three levels, with formations that locals and visitors have given names like "Cathedral Hall," "The Wizard's Hat," "Wedding Cake," and "Frozen Waterfall." A thin guide string runs along the floor to keep you on track. The cave was described in an 1874 issue of Harper's Monthly as "a cave extending 1,100 feet underground enriched by stalactites of a brilliant brown hue," which is still pretty accurate.…