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.
Three years ago, I broke my leg free climbing. It took two and a half years of physical therapy to get back to maybe 80% of what it used to be, and now I have a permanent metal plate. I was lucky it wasn’t any worse.
I don’t think I’ll ever free climb again, it’s just not worth it. However, I also would never do cave diving.