Halfway between Big Bend National Park and San Antonio, off of Interstate 10 and about 15 miles west of Sonora, lies one of the state’s most fascinating natural areas: the Caverns of Sonora. The caves were first discovered at the turn of the 20th century, but they weren’t explored until the 1920s. Intimate group tours limited to 12 guests are offered and cover about two miles of underground caverns. Guests can also take 3-hour photography tours, learning about the caves and how to take quality shots underground. There is also a campsite with 48 hook-up sites, complete with restrooms and showers.