FREE ESSAY ON THE UNDERWATER WORLD

THE UNDERWATER WORLD

The Underwater World
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
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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).
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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 
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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 
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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 
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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 
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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 
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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 
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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.
Bibliography
Bibliography
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.