I would say Marengo Cave. Its easier to get into, and there is so much more for kids to see and experience. You can also choose from two different tours. The Crystal palace is a 1/3 mile, 40 minute tour, and the Dripstone is a mile 60 minute tour. Or if you tjink they can do both i highly recommend you do both. They are very different and both are spectacular!
There is more to see at Maerengo but both are good
Marengo Cave
Defently maerengo
Definitely Marengo
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