Some experts say that because the eyes can see nothing, this torture makes the victim feel like they're about to suffocate and drown. The water torture functions like a one-way valve. Water continuously flows in, while the towel prevents you from spitting it out, thus allowing you to breathe only once. Even if you hold your breath, it feels like the air is being sucked away, like a vacuum cleaner.
Apart from anything else, this water torture is a test of mental fortitude; prolonged punishment surely convinces them mentally that they're about to drown, and before their psyche collapses, they would surely be willing to say anything.
"Water torture," since its inception in the Middle Ages, has been recognized as a form of extreme punishment, hence the United States military's interrogation manual revised in September 2009 explicitly prohibits the use of "water torture" and other methods banned by the Geneva Convention for being "cruel, inhumane, and degrading."
