What's the coolest thing you've ever done?

This is a question you can't just answer off the top of your head . . . it requires a bit of thought.
First, let's eliminate all the Mother Theresa type answers, such as, "Giving birth to my beloved children," or "volunteering in a shelter for homeless puppies," or, "marrying the love of my life." Yeah, yeah, we know.
I'm talking about selfish acts here. Stuff you always wanted to do, and when you finally grabbed the bull by the horns, (this could be an actual answer!!), it was as fabulous as you'd always thought it would be.
I have a few contenders.

1. Whitewater rafting: This is very, very cool. Talk about a rush. And it comes in all different skill and comfort levels, so you can have just as much fun skimming over level 2 or 3 rapids as an expert gets from the big waves. Do I recommend this for others? Yes. But stick with your comfort zone. The bigger rapids can be S.C.A.R.Y.
2. Rappelling: Using a rope to descend from a height. I first did this in college, off the ROTC building at Ohio University in Athens, Ohio. Loved it! Later I had more opportunities with the Boy Scouts. But my ultimate (and final) experience came when I did a story for my former newspaper, and got to free rappel off a 100 foot cliff in Hocking Hills State Park. Do I recommend this for others? Maybe. I'm not going to do it any more, because, although it's a real rush, it's also a bit dangerous from the big heights. Seems like a dumb way to die.
3. Travel: Oh, yeah, travel for pleasure has to be one of the high points of anybody's life -- unless they're a stick-in-the-mud, or travel so much for work that when they get home they just want to stick, period!
I've only recently begun to scratch places off my extensive bucket list. I must highly recommend a cruise to anyone who isn't terrified of water travel. Best. Vacation. Ever. (So far!) Places still on my bucket list include: Iceland (want to see the Northern Lights AND a volcano erupting out of a glacier!!); Ireland; Scotland; England; Italy; Paris; the American West (the month-long driving trip, I'm a thinkin'!); Alaska; Hawaii; Australia. The moon would be great, wouldn't it? Probably not going to happen in my lifetime, alas.
So these are all very cool experiences. But they're topped, I think, by the last thing.

4. The coolest thing I've ever done that was purely selfish was to ride in an Air National Guard Blackhawk helicopter. I got the opportunity when I was working as an editor at the National Boy Scout Jamboree in Fort AP Hill, Va. back in 2010. I did a story that got me a ride. I was harnessed in like a kid in a car seat, sitting right next to an open door 300 feet up in the air while we swooped and banked over the Jamboree for 45 minutes. I took lots of great photos, and had the time of my life. This is something I'll probably never get to do again, and I LOVED every minute of it. Thanks, guys from the Kansas Air Guard. Would I recommend this to others? Oh, HELL yeah.
My advice, in  general, is this: Life is short; often shorter than we can anticipate. Don't take stupid chances, but don't pass up chances stupidly. If  you want to do something . . . REALLY want to do something . . . make like Nike and Just Do It!
So what's on your list? I'd love to hear!