Scientists surmise that thousands of years ago an underground cavern collapsed and created this geological wonder that is designated as a National Natural Landmark. You pass a dozen small waterfalls as you head down 236 steps to the bottom of this botanical wonderland: exotic subtropical ferns and trees growing in a 500-foot-wide, 120-foot-deep sinkhole. You can pack a lunch to enjoy in one of the park's picnic areas. And bring Spot, too; just keep him on a leash. Guided walks with a park ranger are offered Saturday mornings at 10.