Cherokee Sink is a deep water-filled sinkhole in Wakulla Springs State Park. Up to 250' wide and 77' deep, this awesome place to hang out is complete with limestone bluffs and boulders along the water's edge, a surrounding trail to access various viewpoints up along the sink (beware of chiggers), big flat rocks for picnicking or handstands, a disintegrating rope swing, and a tall place to jump off of.
Apparently it used to be a big place for college kids to come and party and fuck up with their trash, but it was closed in 2009 because they didn't have the funds to put in public toilets... or something. Well... IT'S OPEN NOW. Still no toilets, so make sure you do your business at the porta-potty at the head of the trail!