Devils Den is a big hole in the ground. It's makes an interesting dive...once. I have only been in Kings Spring in Crystal River, it's a fairly nice dive IF you get there when a big group has not stirred up the water. If it is stirred up then vis can drop to a couple of feet. Near CR is Rainbow river, it's a shallow river drift dive thats fairly nice and worth doing a time or 2. Of the one's I have been in, my choice would be Ginnie Springs. By the way Tommy, got my cavern cert in Ginnie, the weekend after you were there I think.