Here's a fascinating account of a very fit man subjecting himself to waterboarding in order to answer the question for himself whether every legal precedent that says it's torture is correct or not. Money quote:
The water fills the hole in the saran wrap so that there is either water or vaccum in your mouth. The water pours into your sinuses and throat. You struggle to expel water periodically by building enough pressure in your lungs. With the saran wrap though each time I expelled water, I was able to draw in less air. Finally the lungs can no longer expel water and you begin to draw it up into your respiratory tract.
It seems that there is a point that is hardwired in us. When we draw water into our respiratory tract to this point we are no longer in control. All hell breaks loose. Instinct tells us we are dying.
I have never been more panicked in my whole life. Once your lungs are empty and collapsed and they start to draw fluid it is simply all over. You know you are dead and it's too late. Involuntary and total panic.
There is absolutely nothing you can do about it. It would be like telling you not to blink while I stuck a hot needle in your eye.
At the time my lungs emptied and I began to draw water, I would have sold my children to escape. There was no choice, or chance, and willpower was not involved.
I never felt anything like it, and this was self-inflicted with a watering can, where I was in total control and never in any danger.
And I understood.
Waterboarding gets you to the point where you draw water up your respiratory tract triggering the drowning reflex. Once that happens, it's all over. No question.
Some may go easy without a rag, some may need a rag, some may need saran wrap.
Once you are there it's all over.
I didn't allow anybody else to try it on me. Inconceivable. I know I only got the barest taste of what it's about since I was in control, and not restrained and controlling the flow of water.
But there's no chance. No chance at all.
So, is it torture?
I'll put it this way. If I had the choice of being waterboarded by a third party or having my fingers smashed one at a time by a sledgehammer, I'd take the fingers, no question.
It's horrible, terrible, inhuman torture. I can hardly imagine worse. I'd prefer permanent damage and disability to experiencing it again. I'd give up anything, say anything, do anything.
The Spanish Inquisition knew this. It was one of their favorite methods.
It's torture. No question. Terrible terrible torture. To experience it and understand it and then do it to another human being is to leave the realm of sanity and humanity forever. No question in my mind.