From descriptions I had heard on the news, I thought it was just putting a person on a board and then pouring a bucket of water over their face.
Honestly, that doesn't sound very bad--just spit it out as quickly as possible and you'd also probably get that 'water up the nose' feeling. Turns out it's a bit different. Here's Christopher Hitchens getting waterboarded last year:
I didn't know that it's actually wetting a towel held tightly over someone's face. That's a bit more--it's not so much pouring water on or simulated drowning as simply depriving of breath. That seems to be a large difference, at least to me.
Torture conjures up images of inflicting pain and discomfort externally. On the bright side, pain alone can't kill you. However, to lose control of a vital body function surely has to be terrifying because it could easily be your end. Something comparable, I imagine, would be to use defibulation paddles to induce a heart attack. We're mental in modern times; bruises are so middle ages.
We can weigh the ends and the means of torture, but in the end, we should not torture. (And if we have to stop to think if something is torture, as with waterbording, it probably is.) Torture is disgusting and barbaric.
This is America. The thing that makes this country special is that rather than being leftovers of an ancient kingdom or people who happen share an ethnicity or language, our country was instituted orderly by thoughtful people guided by the ideals of the Enlightenment.
When someone is destructive, it's easy and quick to be destructive in return. It takes foresight, restraint, and maturity to rise above it and take the high path. Moreover, barbarism is the antithesis of civilization and respect for human rights, which is what we're working hard to spread in the first place.
When we torture, our enemies win. Not because they ever destroyed something of ours or defeated us, but because we've voluntarily given up one of our defining characteristics.