Which of the following best describes signs of nitrogen narcosis?

• A. Drunk underwater
• B. Anxiety and tremors
• C. Slurred speech and dizziness underwater
• D. Visual distortions at depth

Answer: (C)

Nitrogen narcosis occurs when increased nitrogen partial pressure at depth depresses the central nervous system, producing effects similar to alcohol intoxication. The most typical signs are cognitive and motor impairment: thinking becomes slower, coordination falters, and speech can become slurred, with accompanying dizziness. This combination—slurred speech with dizziness underwater—best captures the core way narcosis presents, reflecting both the communication difficulty and balance issues divers notice as they descend.

Visual distortions can occur, but they’re not as consistent or defining as slurred speech and dizziness. Anxiety and tremors can arise from other stressors or conditions, and describing narcosis as “drunk underwater” is a broad, less precise way to characterize the effect.