For those who can swim, diving in the sense of scuba diving or deep sea diving is certainly one of the most enjoyable pastimes a person can have. Like anything else, it has its pleasures and its risks, but the allure of the sea is certainly a major part in the life of any avid diver. Still, diving has its risks and perhaps in some sense those risks are greater than in other endeavors. The allure of the sea and the desire to enjoy it as freely as a fish is irresistible to many.
Our fascination with the oceans may have made diving popular in the 19th century, but if so, it was certainly made more popular by the introduction of scuba equipment in the middle of the 20th century. Despite the relatively recent development of deep sea diving apparatus and of scuba diving, men and women have been diving for centuries. Often diving is for pleasure, but at other times it is just another basic survival skill to gather food, hunt for sponges (Hong et al. , 1991) or engage in military endeavors or otherwise.
Until the invention of diving equipment, man was unable to go underwater and remain submerged for any extended period of time. His stay under water was limited by his ability to hold his breath so the problem was how to extend the amount of time underwater and, of course, the obvious solution was to find a means to provide an air supply to a submerged person. In August of last year (2006) while testing the Navy’s new Atmospheric Diving System (ADS) suit off the coast of La Jolla CA, a village of San Diego, Daniel Jackson, a Naval Reserve Diver, made the deepest free dive in history, a total of 2,000 feet. (Guinness, 2006)
Perhaps it is because of the allure of the sea, but long before Jackson, men and women practiced breath-holding. Diving has many useful purposes such as gathering and providing food, military, recreational, research and others so these factors have no doubt added to the allure of diving. Despite the relatively new advent of scuba equipment and deep sea diving equipment, diving has been around for a long time. Of course, it is necessary to hold one’s breath in order to go to any great depth and people have been using breath-holding techniques for diving for centuries.
In ancient Greece, divers held their breath to search for sponges as some people do today, and throughout history some had done likewise in the process of military exploits. For those who wanted to stay underwater longer, the obvious question was how to do so? One solution was to breathe through hollow reeds while submerged. While this technique worked, there were limitations that prohibited it from being a valuable solution. Reeds longer than two feet long do not work well. Today we realize that it is difficult to inhale against water pressure below a certain depth.
Another idea was to put air into a bag that could be used underwater, but that also presented problems, most significantly the fact that it caused divers to breathe in the carbon dioxide that had been exhaled. Although Aristotle wrote about a diving bell in the 4th century BC, all diving was probably done by holding the breath up until the 16th century. (Brylske, 1994; Somers, 1997) Whatever diving was done probably did not exceed depths of 100 feet if that much. The diving bell was the predominant diving apparatus during the 22 centuries from the 4th century BC until the around 1800.
Using this stationary device, divers could get air from the bell and leave to do whatever they were doing underwater returning to the bell periodically for more air. This allowed divers to remain underwater until air in the bell was no longer breathable. By the 16th century, people began experimenting with diving bells. (Somers, 1997) These were actually bell shaped contraptions open at the bottom that were held a few feet from the surface. The diver could enter from the bottom which was open to water and the top part held compressed air, air that had been compressed by the water pressure.
Early designs of the diving bell were refined in the late 1600s and became sizable and sophisticated by 1691 when Edmund Halley patented a ventilated diving bell that allowed divers to remain underwater for as much as an hour and a half. (Gilliam and von Maier, 1992) Even though electricity was not available for electric pumps at that time, manual pumps were used that could pump air from the surface down to divers as early as the 16th century in Europe. However, at greater depths, water pressure became a concern, so metal helmets and leather full diving suits were developed and used to protect divers who went below 60 feet.
This diving equipment was continuously perfected up to the 19th and 20th centuries. By the 1830s, diving techniques that relied on air pumped to divers from the surface had been sufficiently well developed as to allow divers to work underwater for extended periods of time. Although these early techniques worked, they didn’t entirely compensate for some diving concerns. Eventually, the improved technology of the 19th century resulted in compressed air pumps, regulators, carbon dioxide scrubbers and other improvements that allowed divers to remain underwater for longer and longer periods of time.
As diving techniques improved, it became more apparent that there were at least two concerns in diving to depth. One, of course, was the need for an air supply that would eliminate the need to hold one’s breath. The other problem was the need to compensate for depth. (Brylske, 1994; Somers, 1997) In 1905 Scotland’s John Scott Haldane reported the fundamental discovery that breathing is regulated by the amount of carbon dioxide in the blood and in the brain. Haldane developed a method of decompression in stages that allowed deep-sea divers to ascend to the surface safely, information used for today’s decompression charts.
His work and that of the French physiologist Paul Bert increased our understanding of the physiological effects of air-pressure sufficiently to improve out knowledge of the hazards of diving to depth and how to overcome those hazards. Our understanding of the effects and safe limits of using compressed air for diving is due largely to the work of Haldane and Bert. (Gilliam and von Maier, 1992) Today, we realize that decompression, recompression, carbon dioxide and oxygen toxicity are important factors to consider in diving. Diving history can essentially be divided into four periods.
Initially, there was the period of free diving when humans held their breath. Diving time and diving capacity were limited by the availability of air, the build-up of carbon dioxide and the effects at depth of pressure on the body. (Gilliam and von Maier, 1992) Later advances in diving during the second period of diving history led to the creation of heavy walled diving vessels which could maintain their internal atmosphere to that of sea level (1 atmosphere) so as to prevent the surrounding water pressure from being a hazard to the occupants.
Diving bells and bathysphere are two such devices. Bathyspheres are essentially unpowered hollow steel balls that can be lowered from a mother ship by a steel cable. A bathyscaphe is a is bathysphere with a buoyancy control that eliminates the need for a cable. Then there is the submarine, a powered device with its own air supply and which is built so that it can handle all of the problems associated with depth and so it can travel great distances in any direction under its own power.
Bathyspheres, bathyscaphes and submarines required a means to maintain the pressure at one atmosphere around the diver and a means to provide fresh oxygen while getting rid of exhaled carbon dioxide. Carbon dioxide was eliminated by using soda lime, lithium hydroxide and other compounds that take up the carbon dioxide. Later during this period, one atmosphere diving suits were also developed that were flexible and yet able to withstand pressures at great death so as to allow divers to work at depths up to several hundred meters for hours. (Somers, 1997) Diving entered a period of using compressed air next.
The air could be supplied from the surface and delivered to the diver at depth. The hand-operated air compressor was a major advancement in diving history. It had appeared by 1770 and allowed for the development of helmet-hose diving systems that were the predominant diving techniques from 1800 until the mid-1950s. Unlike then final period, during this period of diving the diver is separated from his/her air supply, but has air delivered through a long umbilical cord to a regulator and mouthpiece carried by the diver. At great depth, the diver can be enclosed in a dive suit that can handle the water pressure at depth.
These suits can be cumbersome but the buoyancy of the water can relieve some of their burden. Although diving masks with a regulator, mouthpiece and hose may come to mind when one considers these devices, caissons are also included in this category. Caissons are huge spaces that are supplied with compressed air. Diving bells and rigid helmet diving suits are also grouped in this category. The air that the diver breathes is at the same pressure as that of the water surrounding the diver thus leaving him at risk for decompression concerns such as the bends, air embolism, etc. pon their ascent if they ascend too fast.
To assist with this concern, special mixtures of gas are used that allow divers to dive deeper than with compressed air. These gas mixtures combine oxygen with another gas or gases such as hydrogen, helium and/or nitrogen. (Somers, 1997; Gilliam and von Maier, 1992) The most recent development in diving is diving with compressed air or gas mixtures that include oxygen carried by the diver. This is referred to by the acronym “S. C. U. B. A. ” which is generally referred to as scuba diving.
Scuba stands for self contained underwater breathing apparatus and refers to the fact that the diver carries his or her air supply on their back while diving. Although we may view scuba gear to be a recent development in diving technology, the development of scuba gear can be traced back to 1680 when Borelli, who also experimented with fins and buoyancy compensation, developed a device based on the theory that the hot air a diver exhales could be rejuvenated by cooling and condensing in. (Somers, 1997) Although Borelli’s gear failed, it still represents a step forward in diving theory and technology.
By the first third of the nineteenth century, Condert published a scuba design using a helmet and a compressed air reservoir that fit around the diver’s waist. In 1865, Rouquayrol developed a surface-supplied regulator system that did ultimately have an effect on today’s scuba gear. By 1878, Fleuss and Davis developed a closed-circuit oxygen scuba device that used chemical carbon dioxide as absorbent. (Gilliam and von Maier, 1992; Somers, 1997) The scuba equipment commonly used today was developed by Emile Gagnan and Jacques-Yves Cousteau. Somers, 1997; Cousteau, 1986; Marx, 1990) The two principle types of scuba equipment are open circuit and closed circuit equipment. Open circuit equipment vents the expired air into the water while closed circuit systems all the carbon dioxide to be absorbed and add more oxygen so that the air can be re-used. Scuba divers are at risk for decompression problems if they ascend too fast and various gas mixtures allow scuba divers to go deeper than with compressed air. Scuba diving has a number of advantages over other forms of diving.
The tanks allow the diver to remain underwater longer than would be possible by simply holding one’s breath. Even though scuba allows divers to go deeper than with snorkeling and allows them more freedom than would be possible using compressed air from the surface, its major disadvantage is that the time spent underwater is limited by the amount of compressed air in the tanks. Since time is of essence and all muscle activity decreases the amount of time that oxygen will be available, scuba divers can increase the amount of time they will have underwater with scuba gear if they exert less energy while diving.
Although most divers swim underwater while diving, they can resort to propulsion devices referred to as Diver Propulsion Vehicles (DPVs) commonly called “scooters” to move underwater. The term SCUBA originally referred to rebreathers used by the military for underwater warfare but today it generally refers to open-circuit equipment. However, rebreathers are also classified as scuba gear. The history of diving is certainly to complex and exciting to cover in these few pages, but what few comments have been presented do demonstrate how rich that history is and how far it extends back in time.
Only by considering how far back into history diving extends and the advances diving has made with the passage of time will we truly realize the fascination diving has held for us through time. Perhaps the next great advance in diving will not be man growing gills, but whatever it will be will only add to the present fascination and allure of diving. We can only build on the future of diving by understanding how we arrived at our present level of knowledge and technology.