My days of touring the caves at Mammoth Cave National Park are likely over. I'm only basing this on my dad's experience when I was a kid, but it's a legit concern.

Back in the 70s, our family visited Mammoth Cave and during the tour, we encountered a passageway known as Fat Man's Misery. Well, Dad, being a "portly" gentleman as my great-grandmother used to refer to him, experienced a bit of a struggle getting through it but persevered and made it. Of course, he hammed it up the whole time and we laughed our butts off.

I could probably suck it in enough to get through it too. But my issue is clearance. At 6'5" tall, I'm not sure how keen I am on walking through a cave. I have some minor claustrophobia issues and I'm not sure if they'd rear their ugly head or not.

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But if something like what happened Sunday ever happened again, I wouldn't mind trying to get as far as the Rotunda Room inside Mammoth Cave.

I have never heard of this particular phenomenon. I'm sure it's happened before; weather occurrences are rarely completely unheard of. But how weird would it be to happen upon a fog bank INSIDE a cave?

Too bad they can't MAKE that happen, because THAT is stunning. Of course, if they COULD make it happen, it wouldn't be that big a deal.

How fortunate we are to having one of the world's greatest natural wonders in our own backyard. I hope none of us ever takes it for granted.

LOOK: Stunning vintage photos capture the beauty of America's national parks

Today these parks are located throughout the country in 25 states and the U.S. Virgin Islands. The land encompassing them was either purchased or donated, though much of it had been inhabited by native people for thousands of years before the founding of the United States. These areas are protected and revered as educational resources about the natural world, and as spaces for exploration.

Keep scrolling for 50 vintage photos that show the beauty of America's national parks.