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.
American football, or as I like to call it, Concussion Roulette
Hard to pick one when I’ll never do any of them.
Cave diving.
Extremely risky even for the very experienced. You only need one thing to go wrong and that’s it. Sometimes even the best planning can result in your death because something entirely out of your control happens.
Too late:
E4
Free plummeting. Although that’s just a fancy way to say “jumping off of something really high and then dying when you hit the ground.” The problem is you can only do it once, but it will be the last extreme sport you will ever try.