In 1924, National Geographic expedition members wrote about the wonders of Lower Cave. Visitors today can see the evidence left behind from these and other explorers. Highlights of this tour include The Rookery, with countless nests of cave pearls, the Colonel Boles Formation, and an incredible diversity of cave formations that compete for your attention almost everywhere you look. Ladders at the entrance to Lower Cave sometimes cause participants to back out. If you have a fear of heights or difficulties with ladders, you may wish to consider visiting Left Hand Tunnel instead.

Reservations are required for the Lower Cave tour. To make reservations call 1.877.444.6777 or visit Recreation.gov.

Cost: $20 for adults and $10 for children, Senior and Access Pass holders. Tour participants must also purchase an entrance fee ticket.

Duration: 3 hours

When: Monday through Friday at 1 p.m.

Where: Tour departs from the visitor center lobby.

Requirements: Ages 12 and over. Anyone under 16 must be accompanied by an adult. Participants must be physically and mentally able to safely negotiate cave passages containing fragile formations without harm to the cave, yourself, or others.

Good sneakers or hiking boots, 4 AA batteries, and cotton or leather gloves are also required.