This here is the amphitheater looking down into the caves and below is the walkway down into the caves. We got to Carlsbad Caverns right as they opened at 8:30 am. There was a line to hike into the caves. I highly suggest going later in the afternoon though. At sunset, everyone sits in the amphitheater and watches the thousands of bats fly out of the cave at once, which I think would be very cool.
The caverns were discovered more than 1000 years ago when Indians were looking for shelter. The cavern was formed when an inland sea evaporated more than 250 million years ago. Rainwater gradually seeped through the cracks of the reef and the caverns were created.
The caverns were huge and took about an hour and a half to hike the main tunnels. There are many different private tours and smaller tunnels you can hike through..however my wonderful fear of claustrophobia and the whole thing tumbling on us kept us only in the main tunnel.