Must go... The Narrows. It is in the Texas Hill Country on the Hays/Blanco County line where a coral reef once thrived in land covered by an ocean that is now dry and frozen in time. I've never heard of this place.
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 and acts as headwaters to the beautiful Cypress Creek that flows through Wimberley, sustaining Blue Hole and the Blanco River, recharging the Edwards Aquifer, and finally replenishing estuaries in the Gulf of Mexico."