All in all, such stuff happens. It's certainly not especially smart to hang on to a fence and see if you can ride the jet, but it seems to be a rather popular passtime at that beach, and if I were a bit younger i might just try it myself.
You do risky things for fun when you're young. It's not especially inteligent, but it's... well... fun.
What I don't understand is the sueing part. I did something dangerous, I took my chances, probably had my fun a few times, and on an unlucky day I get what I always knew I could get. It sucks, but it wouldn't have been as much fun without that possibility around in the first place.
Going into legal action afterwards seems a really, really whiny thing to do. It's just not consequent. It would be like if I had sued the guy who gave me his used high-performance skateboard race-wheels, which I wanted for a darn long time, and the first thing I did after mounting them was breaking my arm and tearing my face off. Seriously, what fault is that of his? That he didn't warn me that the new wheels were "realy, really, REALLY fast"? I knew that, that's why I wanted them.