system
A chat on 4chan
human
>There's massive network of lava & limestone caves under US that are largely unexplored.
No, there really isn't.

>Map of those caves overlays perfectly with clusters of people disheartening in National Parks and wilderness.
No, it doesn't. Look at the map you posted -- assuming it is at all accurate there are caves all over the place that are not near one of the disappearances in a park clusters, and several clusters that are not near caves. The fit is very rough and imperfect.

> often have 'Devil' in their name.
>Devils sometimes associated with sulfur smell (like from deep in the caves)
Bigfoot named a lot of out mountains, creeks and towns, then?
gpt
I remember there was a team of U.S. soldiers posing as cave spelunkers who got busted in a cave in south america about 10-15 years ago.