Two tours each under 2 hours
Depending on the number if people in the tour about sn hour and a half
Just week this Memorial weekend and it was approx. An hour and a half. If I remember correctly it's about a half mile in and half mile out. Tour guide stops and educates you on facts and science of the cavern.
Its takes about an hour and a half
For the normal tour it will take about 90 minutes to get everything done and visit the gift shop.
2 hrs max
Thanks! Your answer is awaiting moderation.