General Info

Inner Space Cavern was discovered in 1963 by the Texas Highway Department. During construction of Interstate 35, they were required to do regulation core testing, which required them to drill into the ground. As they did this, they inadvertently drilled into the cave 8 times out of the 20 samples they took. Once they lost those 8 drill bits, they knew they hit a cave. They searched all over the surrounding area but could not find any access into the cave. So, they drilled a 2 foot wide hole down through 33.5 feet of limestone bedrock. The hole became known as the Discovery Hole as it was the very first entrance into the cave (and the only one for several months!). As they explored, they have found over five miles of cave, making Inner Space Cavern the fourth largest cavern in Texas!Inner Space Cavern was discovered in 1963 by the Texas Highway Department. During construction of Interstate 35, they were required to do regulation core testing, which required them to drill into the ground. As they did this, they inadvertently drilled into the cave 8 times out of the 20 samples they took. Once they lost those 8 drill bits, they knew they hit a cave. They searched all over the surrounding area but could not find any access into the cave. So, they drilled a 2 foot wide hole down through 33.5 feet of limestone bedrock. The hole became known as the Discovery Hole as it was the very first entrance into the cave (and the only one for several months!). As they explored, they have found over five miles of cave, making Inner Space Cavern the fourth largest cavern in Texas!