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.
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