This spectacular mexican pit cave is about 1,200 ft (400 M) deep. It is also known as "Cave of the Swallows" because of all the swallows who fly in and out of this vast chasm. Some daring stunt base jumpers leap into this great void and parachute to the bottom of the cave. Normally cavers will rapell down a long rope and then climb the rope back up via mechanical climbing ascenders.