Crystal Lake Cave. It is a show cave with guides and even walkways and a lack of mud, grime and bats. But it does have some well-preserved features.
Squeezing through the underworld while guiding a group of Russian students.
Bob Upton's Cave near Pallisades State Park. It goes back about 20 feet to a small standing-room cavern. Bob was not at home when we visited.
Ice Cave at Maquoketa Caves State Park. The park has a string of sacrificial caves as well as some unadvertised and gated caves reserved for experts.