END – Equivalent Narcotic Depth

END or Equivalent Narcotic Depth is used to express the relative narcotic effect of nitrogen at given depths. Also called rapture of the deep, it impairs divers when they get exposed to a certain pressure. It is different for every diver at different times. The END compares a mixed gas other than air such as nitrox or trimix to what the narcotic effect would if the dive was conducted on air.