Wikipedia:
Waterboarding is a form of torture that consists of immobilizing the subject on his/her back with the head inclined downwards; water is then poured over the face into breathing passages, thus triggering the mammalian diving reflex causing the captive to experience the sensations of .[1][2] In contrast to submerging the head face-forward in water, waterboarding precipitates an almost immediate gag reflex.[3] It can cause extreme pain, dry drowning, damage to lungs, brain damage from oxygen deprivation, other physical injuries including broken bones due to struggling against restraints, lasting psychological damage and, if uninterrupted, death.[4] Adverse physical consequences can manifest themselves months after the event, while psychological effects can last for years.[5] The term waterboarding was coined in 2004.[6][7]
In 2007 it was reported that the Central Intelligence Agency (CIA), the U.S. intelligence service, was using waterboarding on extrajudicial prisoners and that the Department of Justice had authorized the procedure.[8][9] Al-Qaeda suspects upon whom the CIA is known to have used waterboarding are Khalid Sheikh Mohammed, Abu Zubaydah, and Abd al-Rahim al-Nashiri.[10][11] According to Justice Department documents, the waterboarding of Khalid Sheik Mohammed provided information about an unrealized terrorist attack on Los Angeles.[12]
Of course, if you are married to Khalid Sheik Mohammed, I’d probably skip the waterboarding and just get divorced. Guys like that are explosive when you least expect it.