“There you are, totally weightless, quietly soaring just above the sea floor with only the smallest amount of physical exertion. Small fish come out of their holes to look at you. How about that? You are the curiosity. You are the thing that does not belong. Perhaps this is why you dive. You are taking part in exploring man’s last ecological frontier. The very thought would excite anyone whose blood still flows in his veins. The diver is the observer, he looks at everything he can. He totally forgets the outside world” (Reseck 4).
When I first read this piece, I got goosebumps. For years man has explored this vast universe, spending millions of dollars, and only making a tiny scratch on its surface. For me, to be able to explore a world completely different from mine sounds like an opportunity of a lifetime. When I had to choose a topic for my senior project, scuba diving was the most compelling of all. This paper is about the development and use, the techniques, and the physiological concerns of scuba diving.
Man underwater dates all the way back to the Iliad, but sports diving for fun and for a profession is fairly new. If one has ever been underwater, he should know that breathing is impossible. In the early 1940’s, Jaques Yves-Cousteau, a Frenchman, developing something that is now a very important asset to scuba diving. It is known to us as a “regulator.” The regulator conserved air by releasing only the amount of air the
diver needed to breathe. This increased the time the diver could stay down on one tank of air to about one hour if he were in shallow depths. Cousteau’s regulator was simple and inexpensive and marked the beginning of the sport of scuba diving. The sport grew somewhat slowly through the late 40’s and early 50’s because, although the diver could now stay underwater for an extended period of time, in most parts of the world the water was so cold that he was forced to leave the water after a short time (Reseck 16).
In the early 1950’s, rubber suits were designed. They were used to keep the diver warm. These old “dry suits” were worn over long underwear and sweat suits or sweaters. The clothing acted as an insulator, and the rubber suit was used to simply keep the insulation dry. But when the easily punctured “dry suits” were torn, the insulation became wet, thus causing the insulation to be ineffective. But a new suit, called the “wet suit” was invented. The wet suit actually strapped a thin layer of water next to the diver’s body, which soon heated up to body temperature and acted as insulation. Nowadays, foam neoprene is used for all wet suits. When the demand for wet suits increased, manufacturers developed the standard small, medium, and large sizes. As the market continued to grow, the neoprene material was improved by making it softer and more flexible. A backing was also added on the neoprene to increase its durability and service. The market grew larger still, and ready made suits came in extra small, small, medium, medium large, large, and extra large sizes. Today, almost anyone can walk into a store and come out with a good suit that fits (Reseck 17).
Scuba diving can be very dangerous and, if not approached safely, one must know the precautions and dangers before jumping into water to dive. There are several ways to dive underwater. One way is the Pike Surface dive. Start from a prone position on the surface. Sweep both arms back toward the hips at the same time and bend sharply at the hips so that the head and trunk point directly toward the bottom of the pool. With palms facing forward, bring the arms up forcibly, in line with the head, and lift both legs–straight and together–out of the water so that they, too, form a straight line with the body. Let the weight of the legs force the body to submerge. Do not kick until the feet are below the surface, then either kick for greater depth or straighten out for an underwater swim (Counsilman and Drinkwater 29).
Another dive is the Feet First dive. Tread water over the spot where the dive is to be made. Raise the body out of the water with a strong kick and a downward push with the hands and arms. Then straighten legs, point toes, and raise the arms overhead. The weight of the upper body and the arms will force the entire body under the surface. When the downward motion stops, bend at the hips and, with and underwater pike, either continue the dive headfirst or level off to swim (Counsilman and Drinkwater 29).
The mask, the snorkel, and the fins are three of the most important tools in diving. Occasionally, water may seep into the mask, or the mask may become dislodged and flooded while the diver is under the surface. Sometimes a diver can simply surface when the mask becomes flooded, but it may be necessary to clear the mask before surfacing in order to have visibility during the ascent. Grasp the mask
and pull it away from the face to allow the mask to flood. Roll the head to one side so that the face plate is turned to the surface. Hold the uppermost side of the mask firmly against the face, and exhale into the mask through the nose. The air trapped in the mask will fill the space and force the water out under the bottom edge. Some divers prefer to clear the mask by holding it firmly against the forehead and tilting the head back until they are looking up at the surface before blowing into it. Common errors are failing to tilt the mask toward the surface, pressing the top edge so tightly against the face that the mask is pulled away from other parts of the face, and allowing air to escape under the top edge of the mask by failing to hold the mask firmly in place (Counsilman and Drinkwater 31-33).
The snorkel is a critical tool for breathing underwater. Most divers attach the snorkel to the mask strap so it cannot be easily lost underwater. First, slip the mouthpiece into the mouth and bite down on the rubber projections with teeth. The wide flange should fit between the teeth and lips. It is common for the snorkel, stand in shallow water, take a deep breath and submerge until the snorkel is completely filled. Straighten out until the back of the head is clear of the water but the face is still submerged. Next, make a quick hard blow to clear the water from the tube. Now you should have a clear snorkel (Counsilman and Drinkwater 33).
The fins are what make you move through the water in a faster and less rigorous fashion. Walking in fins on land should not be done because they are extremely awkward and could cause a fall. In shallow water, it is easier to walk backwards if you move slowly and slide the feet along the bottom. When the diver is
equipped with fins, the hands are rarely used and held at the sides to help keep the body straight. When the fins are used, the most common kick is the flutter kick and is used on the surface and underwater. The legs are to stay relaxed. To get the full effect of the fins and to avoid necessary fatigue, kick at a slightly slower pace than usual. The toes should stay pointed, and the fins should be completely submerged (Counsilman and Drinkwater 33-34).
When diving, the “buddy system” should always be used, and all equipment should be placed in reach from the dive site. A buddy is there to help you check your gear and, when underwater, to help you in case of an emergency. After you are in the water, put on the fins, mask, and snorkel, and, carrying a weight belt, walk slowly backward to the middle of a shallow area. Sit on the bottom with the weight belt across your thighs. When inhaling, the body should make a slow rise. If it does not rise, then the weight should be decreased. This makes the body neutrally buoyant. Always make sure the mouthpiece and mask are clear. Free ascent should also be learned in case of emergency and the diver must ascend without his gear. The ascent is made slowly, and a constant exhalation of air is required. If you hold your breath during an ascent after breathing compressed air, and air embolism can be caused. This is when air escapes the lungs and enters the bloodstream, causing bubbles to form in the veins. These bubbles block the blood flow to the brain, causing death. Always exhale during a free ascent. The “buddy breathing” and “ditch and recover” methods are also important in diving. Buddy breathing is when you use your partners’ air during a dive if yours is not available. The mouthpiece is to be switched back and
forth every two breaths. The ditch and recovery is when a diver ditches his gear, and recovers all of it in ten feet of water. These are all a few of the techniques used in scuba diving. In scuba diving, you can always learn something new. There are may techniques to learn and can always be improved (Counsilman and Drinkwater 34-39).
In diving, there is always a chance you could be hurt. Safety is crucial, and there are quite a few physiological concerns in the sport. When descending in the water, Boyle’s law goes into effect immediately. As the water pressure surrounding the diver increases, the volumes of air both inside and outside the body of the body decrease in size. This pressure creates a compressing effect on the body that can result in injuries called Barotrauma. This can be avoided by equalization. The two major forms of Barotrauma on descent are internal and external squeeze. The sites of internal squeeze include the middle ear, the sinuses, and, occasionally, the teeth and intestines. As water pressure increases on descent, the air space in the middle ear is reduced, causing a vacuum, with the outside water forcing the flexible eardrum inward. If the internal air pressure is not equalized, the eardrum may become perforated. The sinus squeeze is when the sinuses are blocked. There are four sinuses that are filled with air and called the frontal, ethmoidal, maxillary, and sphenoidal, and come in pairs. The sinuses must be equalized just like the middle-ear space. Due to head colds, allergies, sinusitis, or smog, the sinus may become blocked, thus causing a sinus squeeze (Griffths 71-76).
External squeezes are caused by the divers’ equipment, such as the mask or wetsuit. When an equipment squeeze occurs, body tissues are pulled out and away
from divers, rather than pushed into them. The mask squeeze, which may be the most common external squeeze, is caused by the inability to equalize the air pressure between the mask and the face on the diver’s descent. To prevent a mask squeeze, the diver should exhale through the nose when suction is experienced on the face. A slow descent is also a way to help avoid this problem. A suit squeeze is another kind of squeeze to avoid. This is rare, but air pockets form between the suit and the skin and blood vessels on the surface of the skin could rupture. To prevent a suit squeeze, one must vent the suit of air and fill the former air pockets with water (Griffiths 76-78).
The ascent is the same to the descent in relation to Boyle’s law, but in the ascent, the surrounding pressure decreases, causing air pockets to expand. The two most common types of ascent problems are lung overexpansion and decompression sickness. In lung overexpansion, when a diver breathing compressed air returns to the surface, air in the lungs will expand due to the decreasing water pressure. A diver must breath regularly on the ascent in order to allow this reexpanding air to vent itself normally. Breath holding, uncontrolled ascents, or airway blockage could cause the expanding air to rupture the air sacs in the lungs, allowing air bubbles to enter the body and resulting in tissue damage, blood circulation blockage, or both. Lung overexpansion can be avoided through self-control. Divers should be able to perform a controlled ascent at any time, with normal breathing or exhaling slowly along the way. Scuba divers must never hold their breath while ascending (Griffiths 78).
Decompression sickness, aka: “the bends”, is one of the most feared diving maladies. With increasing depth, the partial pressure of nitrogen also increases. As
the partial pressure of nitrogen elevates, it becomes more soluble in the tissues of the body. At the bottom, the diver with nitrogen dissolved in the tissues and bloodstream experiences no apparent problems. However, when ascending, significant pressure/volume change occur. If the rate of ascent is faster that the ability of the body to vent nitrogen through normal breathing, the nitrogen gas will expand and “bubble-out” of solution. To avoid the bends, diving well within the limits of the U.S. Navy no-decompression tables and following them is the only way (Griffiths 81-82).
Hyperventilation, or shallow water blackout, has more potential to occur on skin dives rather that scuba dives, but may occur on both. Hyperventilation results when rapid, forced exhalations significantly lower the levels of oxygen and carbon dioxide in the bloodstream, which may lead to unconsciousness. To treat hyperventilation, the airway should be opened by hyperextending the neck, mouth-to-mouth respiration may not be necessary if the carbon dioxide level build up and triggers the breathing mechanisms, which often happens (Griffiths 85).
In conclusion, scuba diving is not a simple sport. There are many complexities that go along with it. In time, it has come along from being a difficult sport that is only allowed for a selective few, to a sport that almost anyone can participate in. The improvement in its technology makes it much easier for others to learn. Also, more research has been done on it, and now there is almost nothing more to research about it. It is a very complex topic due to the scientific side of it. There are many scientific laws and there are many restrictions related to it. The only drawback of learning how to scuba dive is the cost. But if you are willing to spend about $450 and want to learn
a lot more about scuba diving than the underwater portion, then by all means–go ahead. After all, it is a completely different world down there.
Counsilman and Drinkwater. Beginning Skin and Scuba Diving. Belmont, CA: Wadsworth Publishing Company, Inc. 1964.
Griffiths, Tom. Sport Scuba Diving in Depth. Princeton, NJ: Princeton Book Co., Publishing. 1985.
NAUI–Adventures In Scuba Diving. St. Louis, MO: Mosby–Year Book, Inc. 1995.
Nonnelly, Doug. Personal Interview. 1 Nov. 1998.
Reseck, John. Scuba–Safe and Simple. Englewood Cliffs, NJ: Prentice Hall, Inc. 1975.