We were fortunate to obtain a site at the very popular Pedernales Falls state park. The park's main attraction is the Pedernales Falls which drops about 50 feet over a distance of 3000 feet, and the cascading falls are formed by the flow of water over the tilted, stair-step effect of layered limestone.
Since it is quite a hike to the river, and I didn't trust the river, we decided to take the hike to Twin Falls overlook instead. It turned out to be a pretty strenuous hike so we got a good workout.
While at the park we saw deer, roadrunners, rabbits and many birds.