Waterboarding is a torture technique. Period. Waterboarding is a controlled drowning that, in the American model, occurs under the watch of a doctor, a psychologist, an interrogator and a trained strap-in/strap-out team. It does not simulate drowning, as the lungs are actually filling with water. There is no way to simulate that. The victim is drowning. How much the victim is to drown depends on the desired result (in the form of answers to questions shouted into the victim’s face) and the obstinacy of the subject. A team doctor watches the quantity of water that is ingested and for the physiological signs which show when the drowning effect goes from painful psychological experience, to horrific suffocating punishment to the final death spiral.
[Malcolm Nance, former Navy SERE chief instructor and Navy SERE manual author]