With the objective of getting to San Antonio, we looked at the map and found that Sonora, TX, was more or less mid-way from Fort Stockton. And, as luck would have it, Sonora is home to the Caverns of Sonora. Are you sensing a theme here? So far on this trip we have visited Kartchner Caverns and Carlsbad Caverns.
The Caverns of Sonora is privately owned where Kartchner Caverns is an Arizona state park and Carlsbad Caverns is a National Park. With only about 3 miles of developed passages, the Caverns of Sonora is not the biggest or deepest cave system, it is impressive nonetheless.