Crystal Cave is beautiful and easy to go through as you walk on paths with handrails and stone steps. Some of the notable formations in the cave include the Upside Down Well, Rainbow Falls, the Cathedral and symbols that indicate Native American habitation.
It's considered a historic site and there is an admission charge. Parking is abundant and it's easy to get to the cave.
Definitely not recommended for children or those with any physical problems. It's not a strenuous cave tour (it's a guided tour), but you do have to walk through it so keep that in mind.