Which type of diving poses the greatest risk for nitrogen narcosis?

Deep diving poses the greatest risk for nitrogen narcosis because this condition is primarily associated with the increased partial pressure of nitrogen at greater depths. As a diver descends beyond approximately 30 meters (about 100 feet), the pressure increases, and nitrogen dissolved in the body tissues becomes more concentrated. This heightened pressure can lead to a change in the behavior of nitrogen, causing it to affect the central nervous system, similar to an anesthetic effect.

The symptoms of nitrogen narcosis can include impaired judgment, euphoria, and other cognitive dysfunctions, which can significantly impair a diver's ability to make decisions and respond effectively in critical situations underwater. While recreational diving and shallow diving are also associated with risks related to other physiological issues, such as decompression sickness, they do not involve the same level of nitrogen pressure that deep diving does. Freediving, on the other hand, relies on breath-holding and does not involve the breathing of compressed gases, thereby minimizing the risk of nitrogen narcosis. Therefore, deep diving is distinctly recognized for its higher susceptibility to nitrogen narcosis due to the physiological effects of elevated nitrogen levels under increased pressure.