'I apply the Abraham Lincoln test for moral casuistry: "If slavery is not wrong, nothing is wrong." Well, then, if waterboarding does not constitute torture, then there is no such thing as torture.' - Christopher Hitchens, "Believe Me, It's Torture"
In the article linked above, Hitchens recounts his experience of being waterboarded. It includes video and is worth reading. Indeed, I would go so far as to call it neccesary reading.
h/t Lippard Blog