Nitrogen narcosis, also known as "rapture of the deep," is a narcotic sensation that divers usually experience at depths beginning at 100 feet. This is caused by the increased pressure of the nitrogen in the body, and its effects intensify as you dive deeper.

The symptoms of nitrogen narcosis are often compared to alcohol intoxication. It impairs judgment and motor skills, so divers experiencing serious narcosis pose a danger to themselves as well as those they dive with.

Individuals vary in their tolerance to nitrogen. Some divers are seriously affected at depths approaching 100 feet, while others show little to no impairment. A diver's tolerance can also vary from one dive to another, so never assume that you know your personal tolerance to nitrogen narcosis.