"To see what is there" has been reason enough most of the time.
I am almost certain that there will be evidence of native incursion into the cave. Its been there a long time; the natives have been there a long time. Young bloods with nothing to lose are always doing damn-fool things like that.
Everest is a pretty clear example of native people not bothering to do stupid things until white people show up and get them tangled up in the mess.
Or the military.
Did you know there's a tiny bit of Canada that is further south than the California-Oregon border?
And that is one of the more accessible areas, there are still plenty of lakes where a water plane can land and there are logging trails every 30 km or so.