Texas, San Antonio Missions National Historical Park
Balmorhea State Park has the largest spring fed pool in the world. It's in West Texas- 2 hours north of Big Bend National Park in the foothills of the Davis Mountains. The pool is 20+ feet deep in parts & is great for scuba diving & snorkeling. The lodging around it was built by the CCC in the 1930s. Worth visiting after a trip to Big Bend!