Compared to many Fredericksburg-related attractions, Old Tunnel State Park may not be as popular as Enchanted Rock or other nearby attractions, but what it lacks in some areas, it more than makes up for in others. The park is terrific for hiking, bird-watching, and general wildlife sightings. The half-mile trail can be challenging, and picnic tables are available, but you’ll need to bring your own water, as there is none available at the park. However, OTSP has something special to offer, if only during half of the year.

Beginning in May, millions of Mexican free-tail bats migrate to the old tunnel, that is their home through October, and emerge in the evenings—captivating thousands of onlookers as the sky darkens from their numbers. The bats are treasured, albeit part-time tenants, so many of the park rules are for their protection and your safety. Guests must stay on the designated trail and are not allowed to approach the tunnel, smoke, or bring pets. However, bat flight viewings occur each evening, and several educational exhibits can be seen along the trail. There are two viewing areas and special tour reservations will be accepted for groups.