Jacob's Well -- Wimberly, Tx: One of the most significant natural geologic treasures in the Texas Hill Country. It is one of the longest underwater caves in Texas and an artesian spring. Jacob’s Well surges up thousands of gallons of water per minute.
one of seven springs that are located in the private Ginnie Springs park (northern Florida), a cave divers paradise. For non-divers there is still plenty to see when snorkelling. (The intense blue colour is due to the water depth at the cave opening).