Once a popular hangout for college kids in the 70s, the Devil's Millhopper is a 120-foot deep, 500-foot wide sink hole in Gainesville, Florida. The boardwalk is currently under construction from damage due to Hurricane Irma. Photos and details from the Florida State Park's website.
Named for its resemblance to the hopper of a mill, this limestone sinkhole has been a site of interest for generations of biology students at the nearby University of Florida because of its unique ecosystem. A natural repository for animal bones and fossils, the sinkhole's name also refers to the belief that animals passed through the hole on their way to meet the devil.
Fed by twelve springs of varying sizes, the pond at the bottom of the sinkhole is dramatically cooler in the summer months than the air at the surface due to the depth and shade from the tree canopy above. Significant fossils have been found at the bottom of the pool, ranging from shark teeth and marine shells to the fossilized remains of extinct land animals.
A fun course for hikers and pedestrians, the Devil's Millhopper now features a wooden boardwalk for viewing purposes with 236 wooden steps and an observation deck at the bottom. This boardwalk/staircase allows visitors to observe the unique landscape without leading to further soil erosion.