Here's a video showing what waterboarding is.
The fact that you can even watch this video in its entirety would probably tell you that it isn't.
An acquaintance of mine who went through officer's training in the Marine corp told me of an exercise where his whole unit was awakened at midnight and made to go through a tube a quarter of a mile long.
Sounds easy enough until the instructors lock the gate behind them and tell them they have to come out the other end and that none of them can come out until they all come out.
That sounds like no problem until they start going though the tunnel and it turns out that some of the guys are too big to get through the tube.
They spend the entire night working the bigger guys through that tube.
Can you imagine?
Stuck in a pitch dark tube all night with a bunch of sweaty ass marines.
Is that torture?
I think I'd take the waterboard.