The primary effect of nitrogen narcosis on a diver is a state of euphoria and exhilaration. This phenomenon occurs when divers descend to depths greater than about 30 meters (100 feet), where the partial pressure of nitrogen increases. The higher pressure causes nitrogen to dissolve more readily in the body’s tissues, particularly affecting the central nervous system.
As a result, divers may experience alterations in cognitive functioning, motor skills, and sensory perceptions. The sense of euphoria can make divers feel unusually carefree or overly confident, which can lead to poor decision-making and risk-taking behavior underwater. This effect is sometimes referred to as "rapture of the deep." Being aware of this state is critical for divers to ensure they can recognize the signs and manage their behavior while diving, thereby maintaining safety.
While other effects on the body during diving, such as those related to oxygen absorption or heart rate, can occur, they are not the primary considerations with nitrogen narcosis. Similarly, severe anxiety and panic are not characteristic of nitrogen narcosis, but rather, these emotions might arise from other factors such as inadequate training or unexpected stressors during a dive. Understanding the euphoric and potentially disorienting effects of nitrogen narcosis is thus vital