Best For
Bat viewing, evening programs, short nature walks, railroad history, birding, and quick Hill Country stops
Top Season
May through October for bat emergence, with the biggest evening spectacle typically building later in summer
Standout Feature
A former railroad tunnel that becomes a seasonal roost for up to 3 million Mexican free-tailed bats
Trip Style
Short day stop, evening bat program, wildlife outing, or scenic add-on to a Fredericksburg or Comfort road trip
Why Visit Old Tunnel State Park?
Old Tunnel State Park proves that a park does not have to be large to feel memorable.
This is not a camping park, a swimming park, or a long-hike destination. It is something much more specific. Old Tunnel offers one of the clearest examples in Texas of how a former human-made structure can become an important wildlife refuge. The abandoned rail tunnel is now a seasonal home for millions of bats, and that transformation gives the park its character.
The evening bat emergence is the reason most people come, but the park works because it combines more than one kind of appeal. There is wildlife drama at dusk, a short nature trail during the day, and a real piece of Hill Country railroad history built into the landscape. For travelers who enjoy places with a strong story, Old Tunnel feels bigger than its acreage suggests.
It is also one of the easiest specialty parks to add to a Hill Country itinerary. You do not need a full day to enjoy it. You just need the right season, a little planning, and the willingness to show up in the evening and let the bats do the rest.
Things to Do at Old Tunnel State Park
Old Tunnel offers a focused experience rather than a long list of activities, but what it does well is truly distinctive.
Watch the Bat Emergence
The main event is the evening bat flight. From May through October, the tunnel is home to up to 3 million Mexican free-tailed bats and about 3,000 cave myotis bats. At dusk, the bats spiral out of the tunnel and climb into the sky before spreading out to feed.
Choose an Upper or Lower Viewing Area
The park has two bat-viewing areas. The upper viewing area gives a more panoramic look at the emergence, while the lower viewing area offers a closer view. Both require advance tickets during bat season, and the lower area is only open to visitors age 4 and older.
Walk the Nature Trail
During the day, visitors can take the short nature trail. It is less than one-half mile, but it gives you tunnel views, interpretive signs about bats and railroad history, and a simple way to enjoy the setting without committing to a longer hike.
Learn the Railroad Story
Old Tunnel is as much a history stop as it is a wildlife destination. The tunnel was originally built to help rail traffic move through the ridge known as Big Hill. That story adds a deeper layer to the visit and explains why the bats now occupy a place that once served a completely different purpose.
Bird-Watch and Look for Wildlife
Texas Parks and Wildlife also highlights bird-watching and wildlife viewing here. Even outside bat season, the park can be a quiet stop for people who enjoy a short interpretive trail, Hill Country views, and a more natural setting than a typical roadside pull-off.
Stargaze After Sunset Programs
The park occasionally hosts astronomy programs, and the evening setting naturally lends itself to a darker-sky feel than visitors may expect from such a small site. Even without a formal program, sunset and twilight are part of what make the park memorable.
Old Tunnel is best when treated as a timed experience rather than a flexible all-day park. In bat season, reservations and arrival planning matter more than trail maps or campground choices.
Best Time to Visit
May through October is the core season because that is when the bats are in residence and the evening emergence becomes possible. If your main reason for going is the bat flight, that is the only window that truly matters.
Later summer can be especially dramatic because Texas Parks and Wildlife says the colony grows when females return with their young and the tunnel population swells to around three million bats. That is when the evening emergence can feel most spectacular.
Outside bat season, the park is still open during the day for the short trail and interpretive visit, but the experience is much simpler. For most people, the best visit is an in-season evening trip planned around bat-viewing tickets.
May–October for bats
Late summer for peak spectacle
Day visits year-round
Visitor Planning Notes
- Daytime entry is free.
- After 5 p.m., May 1 through Oct. 31, every person in the park needs a bat-viewing ticket.
- Tickets must be purchased in advance; they are not sold on site.
- The short trail is open year-round from sunrise until 5 p.m.
What to Know Before You Go
Old Tunnel State Park is easy to misunderstand if you expect a normal state park. There is no camping, and there are only a few basic daytime activities. The park is best thought of as a highly focused wildlife and history site built around one extraordinary seasonal event.
Planning matters because the main experience is time-specific. During bat season, you need advance tickets if you will be in the park after 5 p.m. The upper and lower viewing areas have limited capacity, and the lower area has age restrictions because of the bats’ sensitivity to noise.
It also helps to bring your own drinking water. Texas Parks and Wildlife says water is not available in the park. Visitors should stay on the designated trail, avoid approaching the tunnel, and remember that this is a refuge first and a visitor destination second.
Facilities and Access
Facilities here are intentionally simple. The park has picnic tables, a short nature trail, interpretive signs, and portable toilets in the overflow parking area. It is not built for long stays, but it is well suited to a short visit with a clear purpose.
Both the upper and lower bat-viewing areas include accessibility features. The upper area includes dedicated ADA parking and a very short hard-packed trail to the viewing deck, while the lower viewing area is also described by Texas Parks and Wildlife as ADA accessible.
Since there is no overnight lodging in the park, travelers who want to build a longer trip usually pair Old Tunnel with nearby Hill Country towns or overnight stays in other state parks.
Park History
Old Tunnel State Park is a strong example of how Texas landscapes can move from transportation history into wildlife protection.
Old Tunnel State Park’s defining feature is the railroad tunnel itself. Texas Parks and Wildlife says the tunnel was part of the effort to connect Fredericksburg with San Antonio when rail travel could not easily climb the ridge known as Big Hill. The tunnel became the solution to a difficult Hill Country engineering problem.
The San Antonio, Fredericksburg, and Northern Railway used the tunnel until 1941. After the line was dismantled during World War II, the tunnel’s human purpose ended, and a different set of residents moved in: bats. That shift from transportation corridor to bat refuge is what gives the park its unusual identity today.
Texas Parks and Wildlife acquired the property in 1991, and the State Parks Division took over management in 2012. At just 16.1 acres, Old Tunnel is the smallest state park in Texas, but its history, wildlife value, and seasonal bat population give it a significance that far exceeds its size.
Nearby Attractions
Old Tunnel works especially well as part of a bigger Hill Country outing. Its location makes it easy to combine with wine-country drives, Fredericksburg visits, scenic back roads, and nearby overnight stops.
Fredericksburg
Comfort
Luckenbach
Hill Country scenic drives
Nearby state park overnights
Who This Park Is Best For
- Visitors who want one of the best wildlife-viewing evenings in Texas
- Families looking for a short but memorable Hill Country stop
- Birders, photographers, and nature lovers
- Travelers interested in railroad and regional history
- People building a Fredericksburg or Comfort weekend with a distinctive evening outing
Frequently Asked Questions
These answers cover the questions most visitors ask before planning a trip.
What is Old Tunnel State Park best known for?
It is best known for seasonal bat emergence viewing, its former railroad tunnel, and one of the most unusual evening wildlife experiences in the Texas Hill Country.
Is there an entrance fee at Old Tunnel State Park?
Daytime entry is free. During bat season, tickets are required after 5 p.m. from May 1 through Oct. 31.
Can you camp at Old Tunnel State Park?
No. There is no overnight camping at Old Tunnel State Park.
How long is the trail at Old Tunnel State Park?
The nature trail is less than one-half mile and is open year-round from sunrise until 5 p.m.
How much do bat-viewing tickets cost?
The upper viewing area is currently $2 per person, and the lower viewing area is currently $5 per person for visitors age 4 and older.