47 pages • 1-hour read
Shadow Divers
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Index of Terms
Circle-Runner
This term refers to a malfunctioning torpedo that fails to hit its intended target and instead circles back toward the firing submarine. In the context of German submarines, such as U-boats during World War II, circle-runners posed a significant danger as they could potentially strike the submarines that launched them. The term highlights the risk inherent in submarine warfare of weapons unpredictably turning against their own operators. In the book’s Epilogue, Kurson shares his theory that a circle-runner may have caused the demise of the submarine at the dive site.
Decompression
In deep-sea diving, decompression refers to the process of gradually returning to surface pressure after being exposed to increased pressure at depth. This is necessary to allow dissolved gases, particularly nitrogen, to safely exit the body and prevent decompression sickness, also known as “the bends.” Risks associated with decompression include the formation of nitrogen bubbles in the bloodstream and tissues if ascent occurs too rapidly, leading to symptoms of decompression sickness, including joint pain, paralysis, cardiopulmonary problems, and even death. Proper decompression procedures, including ascent rates and decompression stops, are crucial to mitigate these risks and ensure the safety of divers. The book describes how the highly experienced father-son dive team of Chris and Chrissy Rouse became disoriented and panicked on a dive as a result of nitrogen narcosis, surfaced without decompressing, and died of severe decompression sickness despite rescuers’ attempts to save them.
Narcosis
Nitrogen narcosis is a condition that affects divers at depth due to increased pressure. It occurs when nitrogen, a major component of air, dissolves into the bloodstream at higher partial pressures. Symptoms include impaired judgment, euphoria, erratic emotions, and a feeling of intoxication, similar to alcohol intoxication. As divers descend to greater depths, the effects of nitrogen narcosis can become more pronounced, posing significant risks to their safety. Nitrogen narcosis led to Chris and Chrissy Rouse’s deaths from severe decompression sickness, and Steve Feldman also lost consciousness and died because of it.
Trimix
Deep-sea divers use a specialized breathing gas, trimix, to mitigate the effects of nitrogen narcosis and oxygen toxicity at extreme depths. Trimix is composed of a blend of oxygen, nitrogen, and helium, tailored to the specific depth of a dive. The addition of helium reduces the narcotic effects of nitrogen while still providing adequate oxygen for respiration. Trimix allows divers to safely explore deeper underwater environments by minimizing the risk of nitrogen-related complications. Trimix was new at the time of the discovery of the wreck that Shadow Divers describes. The Rouse father-son dive team could not afford trimix, and their decision to dive with air alone may have led to their deaths.
U-Boat
Short for Unterseeboot, a U-boat is a German submarine that was used primarily during World War I and World War II. These submarines, renowned for their stealth and devastating impact on Allied shipping lanes, played a significant role in naval warfare. Equipped with torpedoes, U-boats were key instruments of Germany's naval strategy. They conducted patrols, convoy attacks, and reconnaissance missions. In the book, the dive expedition’s destination was a U-boat off the New Jersey coast.
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