Hmmm. Man, this just really sucks! I just can't beleive that this HYDROLOCKED it though!? I, like many others have said, have done the same and more in my TJ and JK. Are you sure that it's destroyed? It's not something simple as a clogged air filter, or wet ignition? I have seen both of those stop a vehicle the same way and prevent it from starting untill the filter is changed or the electrics have a chance to dry out. Where did you find out that the engine is destroyed? Is the block cracked? Thrown rod? Horrible self eating noises when trying to crank? Does it even try to crank now? I just can't fathom this, at all. I would hazzard that on a run like that, repeatedly, that it is something electric. Have you had the vehicle the whole time, or have not seen it since it happened?
I guess I am not trying to QUESTION you, as much as I am asking questions out of my own disbelief! Sorry to see and hear that man.
On a side note, and as a good example (unfortunately), if you are ever in a situation like this, and your engine dies. DO NOT ATTEMPT TO RESTART IT!!!! Safety situations not withstanding of course. You are better off being towed out and to start diagnosing the issue first. It could be as simple as pulling the plugs, blowing out water, re-installing and fluid changes. Sorry to see this though.