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Now when you book your tours on recreation.gov make sure and read all the fine print because there

are some more strenuous tours where there is an age limit for how old kids have to be to go on

that particular tour. Age limit as in like if you're too old to go on? There is an age minimum.

Oh okay, there's no maximum age. Is there? No, I mean they let us go.

They didn't check our ID. They let me right there. I did see the rangers talking amongst themselves.

Remember when they held you at the gate for a minute?

This is the Dear Bob and Sue Podcast. Stories from our journey to all the US national parks and

other public lands. I'm Karen Smith. And I'm Matt Smith. We're the authors of the Dear Bob and

Sue series of books. Today we're going underground featuring two South Dakota caves that are in the

national park system, dual cave national monument and win cave national park. Located just 20

minutes away from each other in the black hills, these two caves are completely different. One

features the world's largest concentration of rare box work formations and one glitters and

sparkles with calcite crystals. We'll talk about what makes each cave unique, how they were discovered

and developed more than a hundred years ago and some important things to know before you go.

Thanks for joining us today as we dive into the fascinating underworld of dual and wind caves.

Well, we just had a chance to go back and visit wind cave again a few weeks ago after a 12-year

...