These intriguing phenomena can be found both on land and out to sea. While on the surface they can be a summer’s delightful swimming hole, dive a little deeper and you’ll find a world of discovery and danger. Unless you’re a very experienced diver and are bringing backup, you’re probably best off signing on with a guide. Bahamas Underground is a highly recommended operation specializing in cave and technical diving. For those who choose not to dive, National Geographic magazine’s article “Deep Dark Secrets” from August 2010 offers a spectacular look inside these mysterious treasures.