One of my kids’ favorite books that I would read to them was a goofy story about a Bigfoot that lived in lava tubes by Mount Saint Helens.
The Bigfoot rescues some kid lost in the forest, and I think the guy that hijacked the plane with the millions of dollars is also in that book. (Or at least his money is!)
https://www.amazon.com/Sasquatch-Roland-Smith/dp/0786813342#customerReviews
Heh - I think this must be the book!
In Vietnam they talked about Rock Apes. There was a whole elaborate story about how a Marine Captain and his platoon had a run in with a bunch back in the mid to late 60’s. Yeti’s, Sasquatch, Chupacabra’s and Black Panthers, figments of one’s imagination.