“From  birth, man carries the weight of gravity on his shoulders. He is bolted to the earth. But man has only to sink beneath the surface and he is free”

Jacques Cousteau

SCUBA  diving gives men access to a world of immense beauty. However penetrating into an environment that is hostile to our physiological structure presents us with a myriad of challenges. The feeling of weightlessness and freedom hides the physical changes that are taking place, within our bodies, as we descend deeper and deeper below the ocean surface. SCUBA diving is a sport  that is often addictive because of its allurement and escapism, however it is also an endeavor that must be respected and understood.

The phrase “Rapture of the Deep” first appeared in Jacques Cousteau ‘s book “The Silent World”. It implies a state of extreme happiness,bliss, and ecstasy.  The description was derived from a dive made by  Frederick Dumas, Cousteu’s friend, in 1943. He chronicles the dive: “The light does not change color as it usually does underneath a turbid surface. I cannot see clearly. Either the sun is going down quickly or my eyes are weak.  I reach the hundred- foot knot. My body doesn’t  feel weak but I keep panting . The dammed rope doesn’t hang straight. It slants off into the yellow soup. It slants more and more. I’m anxious about  the line, but I really feel wonderful. I have a queer feeling of beatitude. I am drunk and carefree. My ears buzz and my mouth tastes bitter. The current staggers me as though I had too many drinks.”(The Silent World- pg22). The feeling that Dumas experienced is known today as “Nitrogen Narcosis.”

Nitrogen narcosis is a condition caused by an increase of partial pressure of nitrogen. It is usually encountered at depths of 100 feet and below. In the world of diving it is known as the “Martini’s Law” because the symptoms that a diver feels are similar to that of “one martini on an empty stomach for every 50 feet of depth beyond the initial 100 feet”.(medical dictionary). The diver often becomes irrational  as is further described in The Silent World by Jacques-Yves Cousteau : “ The first stage is a mild anesthesia, after which the diver becomes a god. If a passing fish seems to require air, the crazed diver may tear out his air pipe or mouth grip as a sublime gift.”  Nitrogen narcosis is believed to be caused by high nitrogen pressure on nerve conduction and is completely unrelated to the bends.

The reality is that deep diving presents challenges and physiological changes that are, as yet , not clearly understood. In the case of nitrogen narcosis we can alleviate the danger by recognizing some of the symptoms such as euphoria; wooziness; loss of manual dexterity; fixation of ideas; inability of complex reasoning. All of these symptoms can be easily eliminated by immediately ascending and typically by the time a diver reaches a depth of 60 feet they are completely gone.

Helium,which requires a very high pressure to produce euphoria, is sometimes used as a substitute for nitrogen. Other steps that can be taken to minimize nitrogen narcosis is to refrain from drinking alcohol at least 24 hours prior to diving, avoid stressful situations, stay focused and maintain a low work effort during deep dives.


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