Jacob’s Well in Texas is an amazing crystal clear hole. It’s open to jump and dive in but this doesn’t go without danger. Jacob’s Well is one of the longest underwater caves in Texas. From the opening in the creek bed, the cave descends vertically for about ten meters, then continues downward at an angle through a series of silted chambers separated by narrow restrictions, finally reaching a depth of forty meters.

cheack it: http://www.wherecoolthingshappen.com/amazing-jacobs-well-in-texas/