CNN EarlyStart March 5, 2013 11:48:00
Not probably as close to the surface as this, but you definitely have cavities of this size all over the state of florida. >> reporter: fossils found in this sinkhole show it's been around since the ice age. but no different than the sinkholes we see opening up today. these are just a few of his pictures. but one thing they all have in common is water. >> rain water is going to turn into ground water and that's what's naturally acidic. that's the device that dissolves the limestone and will help create these cavities. >> reporter: what is unusual about this sinkhole, it's easy to get inside. c...