San Solomon Springs

In the middle of the West Texas desert lies Balmorhea State Park, a literal oasis among the scrubland. The river here has been routed into the swimming pool of your dreams, with clear fresh water, a rocky bottom, dozens of fish and marine life, AND a diving board. From the surface, Balmorhea looks like an enormous swimming pool. Under the water (which is deep enough to provide for deep sea diving training), turtles play and fish swim. There's plenty of sprawling lawn for families and picnics, and an adjacent campground for sleeping and moon-gazing. If you ever find yourself in West Texas, this is a must.