Skin diving is the act of going underwater while holding the breath or while breathing compressed air from tanks. Skin diving generally refers to breath-hold diving, the oldest and simplest form of diving underwater. Diving with the aid of air tanks is called scuba diving. Both kinds of skin diving are popular forms of recreation. Many people enjoy exploring the beautiful world beneath the surface of rivers, lakes, and oceans. Recreational divers explore, take underwater photographs and videos, capture tropical fish, and collect shells and other objects.
Professional and military scuba divers perform important tasks while underwater. For example, they repair ships, recover valuable objects, and help build and repair structures. Scientists and students use scuba equipment to help in the study of underwater biology and geology.
Many skin divers carry such equipment as bags made of netting or canvas, knives, and underwater lights and other tools. Small fish can be captured with nets and suction devices. Spears are used to take food. Divers use special cameras to take underwater photographs, movies, and videos.
A diver may communicate with the surface or with other divers underwater with special electronic devices and may employ other electronic equipment to search for ships or lost objects. Special electronic meters and computers are used for safety and to record or display important information. Recreational divers most often communicate with hand signals.
Kinds of skin diving
Breath-hold diving
requires no equipment, but most skin divers wear a face mask, swim fins, and a short breathing tube called a snorkel. The face mask permits clear vision underwater. The flexible swim fins help a person swim with greater ease. The diver breathes through the snorkel while floating or swimming facedown at the surface.
A breath-hold diver may wear a wet suit, a close-fitting coverall made of a material similar to foam rubber, to keep warm in cold water. Some water may enter, but the diver’s body heat warms this water, and the suit holds in the warmth.
Breath-hold divers may also wear a weighted belt and a buoyancy compensator. The weight of the belt helps the diver stay at the desired depth instead of floating upward. The buoyancy compensator, which floats when inflated, also helps the diver maintain the desired depth and serves as a support if the diver becomes tired and wants to rest on the surface.
Breath-hold divers cannot descend deeply because they must continually return to the surface to breathe. Most divers can go 30 to 40 feet (9 to 12 meters) deep and must surface after less than a minute. Some can dive as far as 100 feet (30 meters) and remain submerged from one to three minutes. Breath-hold divers can safely increase their time underwater by remaining relaxed and swimming slowly.
Some divers take two or three deep, rapid breaths before diving. This process, called hyperventilation, enables persons to hold their breath longer. Excessive hyperventilation should be avoided because the diver may misjudge the need to breathe and pass out underwater.
Scuba diving
involves the use of portable metal tanks that supply compressed air for the diver to breathe. A diver using one tank can remain at a depth of 40 feet for about an hour. Strenuous activity or diving deeper will cause the diver to use the air supply faster and greatly reduce the duration of the dive. The word scuba stands for _s_elf-_c_ontained _u_nderwater _b_reathing _a_pparatus.
Scuba gear consists of one or more tanks and a demand regulator that includes the air hose and mouthpiece. The regulator controls the flow of air so that the pressure within the diver’s lungs equals the pressure of the water. The pressure underwater is greater than on land and increases with depth. Serious injury can result if the pressure in a diver’s lungs is not equal to the surrounding water pressure (see Diving, Underwater (Dangers of underwater diving) ).
Scuba divers may also use a mask, wet suit, weighted belt, fins, snorkel, and buoyancy compensator. In warm tropical waters, divers may wear a lightweight suit of colorful fabric instead of a wet suit for protection and warmth. Scuba divers breathe through the snorkel while swimming at the surface and thus conserve the air in the tanks. The buoyancy compensator can be inflated underwater to help the diver maintain the desired depth, to change depths, and to rest on the surface.
Learning to dive
Beginning divers should seek instruction from a qualified teacher who has been certified by a recognized organization. These organizations include the National Association of Underwater Instructors (NAUI), the Professional Association of Diving Instructors (PADI), Scuba Schools International (SSI), or the Young Men’s Christian Association (YMCA). Certified instructors can be contacted at diving equipment stores, colleges and universities, community swimming pools, seaside tropical resorts, and some YMCA’s.
A trained scuba diver with relatively little experience should restrict diving to depths of 60 feet (18 meters) or less. Even experienced divers should avoid depths greater than 130 feet (40 meters). Advanced training and a wide range of supervised diving experience are important before venturing to greater depths.
History
For thousands of years, people have dived underwater in search of food and to gather pearls, shells, and sponges. Early divers used no equipment. Divers probably began using snorkels made of hollow reeds about A.D. 100. By 1300, Persian divers were using goggles made from the polished shells of tortoises.
Independent breathing devices for diving were first tested during the late 1800’s and early 1900’s. In the 1930’s, divers began to use rubber goggles with glass lenses, and also face masks. Two Frenchmen, Jacques-Yves Cousteau and Emile Gagnan, developed the aqualung, one of the first breathing devices with a demand regulator. Cousteau tested the device successfully in 1943.
During the 1950’s, diving began to grow as a recreational sport in the United States. The Underwater Society of America was formed in 1959. It promotes diving safety, sports, and conservation. A number of organizations provide information on skin diving instruction and skin diving clubs. One of the largest is the National Association of Underwater Instructors, based in Montclair, California.
