Personally I’d say cave diving. I was contemplating between that and free climbing soloing but I honestly rather fall to my death than drown in a claustrophobic, dark, cold, silted up cave.
Cave diving is a good one. But also underwater cave diving, if that’s the right term. Seeing pictures of those those “don’t go beyond this point you will die” signs underwater is pretty dang spooky
Don’t read about https://en.m.wikipedia.org/wiki/Nutty_Putty_Cave then. Quite a way to go out, 28 hours headfirst into a crevice you can’t back out of. RIP
I think “cave diving” is generally understood to refer to the underwater variety.
If you’re referring to general cave exploration, that would generally be called “spelunking”