23 miles south of Fredericksburg Texas, lies the smallest state park in Texas. Old Tunnel State Park. 

Named after an abandoned railroad tunnel, Old tunnel state park is home to over 3 million bats in the between the months of may through October. A ticket is required to stay in the park after hours to view the bats emergence. This park is a day/evening visit park only, as camping is not allowed. The park also offers hiking trails that open at sunrise, and close at 5pm. Bring your own water, as there is not water available at the park.