Years ago, we took the kids to Mammoth Cavern's in Kentucky.
I was doing just fine until the guide pointed out two huge rocks. According to him, long ago, a native American (can't say the "I" word anymore" had crawled into the space between the two to harvest Obsidian or some other kind of rock to make knives with and the top rock came down and "Squished" him.
Not to hijack... but about 100 years ago when I was in college at the U of AZ, my roommate was a geology major and got a summer guide job at Colossal Cave.
He took about 5 of us (boys and girls both) on a guided but way off the tourist path tour of the caves.. Lots of crawling, grunting and squirming over, under, around and through the caverns.