One of the most intriguing interpretive tours I’ve joined across the national park system was the “wild cave tour” offered at Mammoth Cave National Park. For six or more hours in sections of the cave off-limits to the more traditional tours we scooted through tight places on our bellies when not able to get by on hands and knees.

Talk volcanoes and national parks and folks usually think of Hawaii Volcanoes National Park, and perhaps Lassen Volcanic National Park. In truth, though, there are at least 13 units of the national park system that have a volcanic past in some form or fashion.