The Physics of Pressure on the Human Body
To understand the physiological effects of deep water, one must first grasp the basic physics at play. At sea level, we experience one atmosphere (ATA) of pressure, but this pressure doubles at just 10 meters underwater. This principle, explained by Boyle's Law, states that as pressure increases, the volume of a gas decreases proportionally. This affects all the gas-filled spaces within the body—the ears, sinuses, and lungs—and drives inert gases, primarily nitrogen, into the body's tissues, a process described by Henry's Law.
Nitrogen Narcosis: The "Rapture of the Deep"
As a diver descends, the increasing pressure causes more nitrogen from their breathing gas to dissolve into their bloodstream and tissues. At depths generally greater than 30 meters (100 feet), this excess nitrogen begins to act as an anesthetic, leading to a state known as nitrogen narcosis. The symptoms are similar to alcohol intoxication, including impaired judgment, poor coordination, and a sense of euphoria. While reversible upon ascending to shallower depths, this impaired decision-making can be fatal, as a diver might ignore crucial safety procedures or signals.
Decompression Sickness: The "Bends"
Decompression sickness (DCS) is one of the most well-known dangers of deep diving, caused by ascending too quickly. During a deep dive, the body absorbs excess nitrogen. A slow, controlled ascent allows this nitrogen to be released gradually through the lungs. However, if the ascent is too rapid, the nitrogen comes out of solution and forms bubbles in the blood and tissues, much like opening a soda can. These bubbles can cause significant pain, tissue damage, and block blood vessels, leading to symptoms such as joint pain, rashes, and fatigue. In severe cases, it can result in paralysis, brain damage, or death.
Types of Decompression Sickness
- Type I: Milder form, often characterized by musculoskeletal pain (the classic "bends") and skin issues like itching or rashes.
- Type II: More severe and life-threatening, affecting the central nervous system, respiratory system, and circulatory system. Symptoms can mimic a stroke.
Barotrauma: Pressure Injuries to Air Spaces
Barotrauma refers to injury caused by pressure differences between the body's internal air spaces and the surrounding water. Proper equalization techniques, such as the Valsalva maneuver for the ears, are essential to prevent this.
- Ear and Sinus Squeeze: On descent, if a diver fails to equalize, the increasing pressure can cause the eardrum to bulge inward, resulting in pain, bleeding, or rupture.
- Pulmonary Barotrauma (Lung Overexpansion): Holding one's breath during ascent is extremely dangerous. As a diver rises, the compressed air in the lungs expands. If not exhaled, this expansion can rupture lung tissue, leading to an arterial gas embolism (AGE), where air bubbles enter the bloodstream and can cause a stroke or heart attack.
Oxygen Toxicity and Other Risks
While essential for life, breathing high concentrations of oxygen under increased pressure can become toxic to the central nervous system. This risk becomes particularly relevant during very deep dives using specialized gas mixtures. Symptoms can include convulsions, seizures, and loss of consciousness, which can lead to drowning. Other risks include Immersion Pulmonary Edema (IPE), where fluid builds up in the lungs, especially in cold water, and hypothermia from prolonged exposure to cold temperatures.
Factors Influencing Diving Risks
Risk factors for diving injuries vary widely. While proper training and adherence to safety protocols significantly reduce risk, personal physiological factors also play a role. Conditions like dehydration, fatigue, older age, high body fat, and pre-existing lung or heart defects can all increase a diver's susceptibility to decompression illness.
Comparison of Common Diving Conditions
| Condition | Primary Cause | Typical Onset | Key Symptoms |
|---|---|---|---|
| Decompression Sickness (DCS) | Rapid ascent; nitrogen bubbles form in tissues and blood. | Up to 24 hours after surfacing. | Joint pain, rash, fatigue, dizziness, neurological issues. |
| Nitrogen Narcosis | High partial pressure of nitrogen at depth. | At depth, typically >30m (100ft). | Impaired judgment, euphoria, memory loss, confusion. |
| Barotrauma | Pressure imbalance in air-filled spaces. | During ascent or descent. | Ear/sinus pain, lung injury, ruptured eardrums. |
| Oxygen Toxicity | High partial pressure of oxygen at depth. | At depth, related to dive profile. | Dizziness, nausea, visual changes, seizures. |
Mitigating the Dangers of Deep Water
To safely explore the depths, proper training is paramount. Certified divers learn essential techniques to manage the risks associated with pressure changes. The most critical lesson is to control one's buoyancy and ascend slowly, allowing the body to properly off-gas the dissolved inert gases. Dive computers are also an invaluable tool, providing real-time data to help manage depth, time, and ascent rates.
Key safety precautions include:
- Controlled Ascent: Never exceed a safe ascent rate and always perform required safety or decompression stops.
- Equalize Regularly: Address pressure changes in the ears and sinuses frequently during descent.
- Breathe Continuously: Never hold your breath while using compressed air, especially during ascent, to prevent lung overexpansion injuries.
- Monitor Your Gauges: Watch depth, time, and air supply closely. A dive computer automates many of these calculations.
- Stay Hydrated and Well-Rested: Fatigue and dehydration are known risk factors for DCS.
- Avoid Flying After Diving: Wait at least 12-24 hours before flying to prevent decompression sickness at altitude.
Conclusion
In conclusion, what happens to your body if you go too deep in water is a series of complex physiological changes driven by increasing pressure. While conditions like nitrogen narcosis and barotrauma can occur at depth, the most significant risks, including decompression sickness and arterial gas embolism, are related to a rapid reduction in pressure during ascent. Through proper training and strict adherence to safety protocols, divers can mitigate these risks and enjoy the underwater world safely. Understanding these dangers is the first step toward a safe and successful dive. For more information, consult the Divers Alert Network (DAN), a leading resource in dive safety and medicine.
