| Old Tunnel State Park | |
| Map: | Texas#USA |
| Relief: | yes |
| Label: | Old Tunnel State Park |
| Label Position: | Right |
| Marker Size: | 6 |
| Location: | Kendall County, USA |
| Nearest City: | Fredericksburg Comfort, Texas |
| Coordinates: | 30.101°N -98.821°W |
| Area: | 16.1acres |
| Established: | 2012 |
| Visitation Num: | 31,816 |
| Visitation Year: | 2022 |
| Visitation Ref: | [1] |
| Governing Body: | Texas Parks and Wildlife Department |
Old Tunnel State Park is a railroad tunnel of the Fredericksburg and Northern Railway, which ceased operations in 1942. The property came under the care of Texas Parks and Wildlife Department, and was officially made a state park in 2012. It is located halfway between Fredericksburg and Comfort on Old San Antonio Road. Since the shut down of the railway, the tunnel has become a bat cave, hosting over 3 million Mexican free-tailed bats and 3000 Cave myotis bats. The bats emerge at sunset during the months of May through October, and viewing is open to the public.[2]
At 16.1 acres, it is the smallest state park in Texas.[3]