This cavern was never seen by Lewis and Clark, but since it is in the area they named it for them. The cavern is up a fairly large hill about .75 miles from the ticket booth. Read the information you are handed very carefully. It is a long walk uphill. We are over 65 yo and made it.
The cavern is different from others we have seen. It is in a vertical orientation, rather than a horizontal orientation like Carlsbad or Mammoth. After entering the cave, we walked down steps and more steps and kept going down. After about an hour of looking at neat formations, we were many feet below where we started. Our guide was really knowledgeable about history of the cave, and the formations. It is different from other caves. Please read carefully the information you are given when buying your ticket.
Check out the geocaches in the area.