"Little known fact: Florida’s best diving isn’t in its saltwater. It’s hidden in the northwestern corner of the state, which is riddled with freshwater springs that flow through mazes of limestone passageways. Few people ever witness the strange sights of these underwater chambers—fossils, sunlight beaming in from holes in the cave ceilings, and even ancient mastodon tusks—because the only way to see it all is by donning a mask and flippers."