The skillful navigation of the polar ice cap by the submarines Nautilus and Skate has focused attention on the roof of the world. But despite the domination of frigid regions by nuclear vessels, high-powered ice breakers, and caterpillar snow tractors, there is still a demand for the services of swimmers, men who can enter areas inaccessible to ships or machines. Immersion in polar waters—bone- chilling, spine-freezing waters—what a great challenge to man! When we constructed the Dew Line across the Arctic coasts of Alaska and Canada, U. S. Navy Underwater Demolition Teams played a prominent part. Underwater Demolition Teams are now in the Antarctic, in company of the scientists engaged in the studies and exploration of the Geophysical Year. However, when the writer first proposed that UDT swimmers accompany the U. S. Navy Expedition to the Antarctic in 1946-47, he was considered to be quite mad by some and an extremist by the most charitable. But swimmers have proved their ability to operate in polar areas, and now serve every task force which enters the ice.
The first purpose in sending swimmers to the polar regions was to blast a way through ice floes and to assist ships in working free from ice jams; secondly, to test the capability of swimmers in the reconnaissance of landing beaches beset by ice. It was obvious after World War II that future warfare would not always be conducted in the tropical areas of the Pacific. The Russian Bear was an Arctic animal, and into his element we would have to go—my underlying reason for sending swimmers to the polar regions. There under actual operating conditions, the UDT personnel proved that they could endure extreme cold water temperatures (29°F) for extended periods of time and also perform vital tasks aside from their primary combat missions— such tasks as underwater inspection of hull damage, changing propellers, recovery of equipment lost through the ice, and the location and the recovery of crashed, submerged aircraft.
A great wealth of scientific endeavor is being directed toward adapting man to the polar environment. Studies have even been made of the personal habits and physiology of the Eskimo. Perhaps—dread the thought— a training requirement for prospective polar swimmers will be a diet of seal oil and whale blubber. Scientists can determine by calculation the approximate minimum water temperature that man can withstand for extended periods and also the approximate amount of protective insulation (a water impermeable sheath over undergarments) required for immersion in waters of various temperatures. Studies have been conducted of long distance swimmers having no protective clothing other than a body grease. The effects of the exercise of swimming in preventing a decline of rectal temperatures in cold waters is being investigated by Dr. E. M. Glaser of the Medical Research Council in England. The problem of extra insulation for the extremities has been studied by Dr. C. H. Wyndon and K. D. McDonald of the South Africa Institute for Medical Research. A wealth of other scientific information relating to adapting man to polar environments is available from the U. S. Naval Medical Research Institute, Bethesda, Maryland, and from the Arctic Aeromedical Laboratory, Seattle, Washington. Undoubtedly, much information is likewise available from the Admiralty Research Laboratory and other British and Canadian research institutes.
UDT swimmers learned much by personal experience in cold weather areas. The experiments conducted were of a practical, empirical nature, to determine the limits of exposure men could withstand, primarily for military purposes. In early experiments within the UDT organization, we quickly found that there was no hope of making polar bears out of humans. It would be necessary to cloth men to withstand immersion in frigid waters and the environment of extreme cold air temperatures. In the Korean War, UDT swimmers were exposed to subzero air temperatures while swimming in relatively warm (39°F) sea water. As the Eskimo very carefully clothes himself in hides, with the fur turned in to the body, so does the underwater swimmer don successive layers of wool underwear under a watertight, close-fitting, rubber sheath. So clad, with only the lips exposed, swimmers can operate for periods of one to two hours in water temperatures near freezing. It is as simple as that, though there is much that can be done to improve the technique. Thought should be given to chemical heating of the suits. The requirement for pressure suits for high altitude flyers is similar to the need of suits for divers. In fact, a case of bends was recently treated by placing the deep sea diver in a high altitude pressure suit.
The physical condition of swimmers is of primary importance. Experience has proved that it is not necessary for swimmers to be exposed to cold for a period of acclimation before entering the polar zones. In modern warfare it is not desirable to maintain military units for long periods in Arctic areas, for reasons of morale, logistics, and training. A man thoroughly conditioned physically (as are all UDT swimmers, in fact, all expert swimmers) can be transported from tropical training areas into the Arctic and immediately subjected to cold without deleterious physical effects. As an example, the UDT swimmers first employed on the Dew Line were flown from Southern California in June. Two days after arrival in Simpson Strait located above the Arctic Circle in Canadian Northwest Territories, Lieutenant (jg) Jon Lindbergh blasted holes through seven feet of sea ice and conducted dives to determine the nature of the sea floor, sea water temperature 28°F. GM1 William Gianotti dove to a depth of 65 feet in 32° water to place a retrieving cable around the major control panel lost overboard at Cambridge Bay, Northwest Territories. This diver worked on the bottom for forty minutes and though chilled through because of a torn suit, accomplished a task vital to the establishment of a main Dew Line site. In another instance, UDT swimmers who had been diving for a period of three months in the waters of the Virgin Islands, sea temperature 86°F, were transported to Newfoundland, where they conducted extensive diving operations off Argentia in sea temperature 39-42°F. The success of these operations was due to excellent physical condition and adequate protective clothing, not to acclimatization.
Men have survived for long periods in frigid seas. This is possible by the generation of heat in the muscles when swimming at a hard rate. As soon as the swim rate is reduced, numbing and loss of body heat will quickly follow and the swim soon terminates. There is a verified instance of an Alaskan fisherman swimming through a night in water off Nome, Alaska. The channel swimmer type can plow through waters in the 45°-55°F range for hours. Men with the massive physique of Lamor Boren, the famous underwater photographer, and that human walrus, Boatswain’s Mate Leonard McLarty of UDT, have much more tolerance for cold seas than the lean, wiry type and can stand long periods of immersion in 50°F waters with no protection. However, there are unfortunately too many records of “man overboard” cases in Arctic waters in the 30°-40°F temperature range, where the man failed to survive, though still swimming when rescued, and immersed for as short a period as ten minutes. Also, when swimmers have torn their suits, even though the area exposed was limited to a small part of the body or extremities, the swimmer is soon forced to give up. The ability of man to withstand cold should not be judged by the capability of a few, as the range of individual tolerance is great. This is also true in relation to other divers’ diseases. Controlled tests of UDT swimmers exposed to oxygen toxicity, nitrogen narcosis, and carbon dioxide poisoning showed surprising variation in tolerance. There seems to be a relationship between the tolerance of the individual to whiskey and to the other toxicides associated with diving. Whether this would hold true to exposure to cold, I do not know.
There are variables in the individual ability of man to withstand immersion in cold water without protection. Guidance rules can be applied to groups of divers in sea temperatures as follows:
80°-90° F: Prolonged swim periods of four to six hours daily for months on end can be conducted with no protective clothing.
70°-80°F: Swim periods of two to four hours are normal. Small loss of body heat occurs. In the lower temperature range of this zone, chilling will commence after two hours.
60°-70°F: The body feels the cold on first entering the water. Men warm up after exercise and can swim from one to two hours without protection. However, shivering is noticeable on coming out of the water. Some retention of body heat can be obtained through wearing a suit of underwear. Some swimmers will require exposure suits in these temperatures. The “wet” suit is recommended. “Wet” suits, constructed of foamed plastic materials (polyvinylchloride) have been in common use by California skin divers for years and are now standard equipment for UDT. Due to swim comfort, ease of entry, and simplicity of repairs, the wet suit is preferred in sea temperature range of 45°-65°F. Principle of the wet suit is based on entrapment of air in the material. Water trapped between the material and the swimmer is warmed to near body temperature, and will not chill the swimmer unless it flows through the suit fast enough to carry away an amount of heat comparable to that which escapes through the insulation.
50°-60°F: Exposure suits are required for all swimmers. The “wet” suit provides quite satisfactory protection in this temperature range. Swims of two to four hours can be conducted without excessive body heat loss while wearing wet suits, but chilling will be experienced.
40°-50°F: The dry swim suit, with one suit of waffle-weave nylon underwear, heavy wool socks, gloves, and head piece are required. Swims of 1½ to 2½ hours duration are possible. Hands and feet will become progressively colder and some discomfort will be felt in latter stages of the swim. Men will shiver after leaving the water. Body temperatures will drop two to three degrees. Some swimmers are capable of using wet suits in this zone, providing air temperatures are above freezing.
28°-40°F: Dry suits plus double suits of undergarments, socks, gloves, and heavy head pieces are required. Ensolite (polyvinylchloride) underwear has been used with success, though the initial buoyancy of the diver is increased, requiring about twelve pounds additional weight to achieve neutral buoyancy. Due to pressure, the buoyancy decreases sharply at depths of twenty feet. In dives of over 100 feet, it may be necessary to drop weight. Swimmers will feel the cold but can be expected to endure immersion for a period of one hour. The extremities may numb, and cold will be felt in the mouth and where facial tissue is exposed. Any leakage in suits will result in immediate chilling and usually terminate the dive. If shivering occurs while submerged, divers should immediately leave the water. On ascent, exhalation must be regulated despite shivering, and forced if need be in case of spasmodic breath-holding due to sudden shock of cold water entering suit. Otherwise embolism may occur. Body heat loss of 3 to 5 degrees can be expected. Divers who show the effects of cold should be given warm showers or baths, gradually increasing the heat; then placed under warm blankets until body heat attains normal temperature.
The fit of an exposure suit, either dry or wet, is of such importance that UDT personnel have suits tailored to measurement for each individual. This is quite simple when using foam rubber, vinylchloride material. In dry suits, sizes of small, medium large, and extra large are the minimum range. Particular care of fit at the neck, wrists, and ankles to prevent binding and the cut-off of circulation is required.
Nylon “waffle-weave” underwear is much more satisfactory than wool. Two pairs of “waffle-weave” under a dry suit will give adequate comfort for 45 to sixty minutes in 30° to 40°F water temperatures. It is practical to use separate gloves, which may be sealed to the sleeves by overlapping on a rigid bracelet and bound with medical adhesive tape. One pair of nylon plus one pair of woolen gloves under watertight outer gloves gives good protection for the hands. Heating pads for hands and feet appear logical, though this simple device has not yet been experimented with by U. S. Navy UDT. The feet are the most difficult part of the body to keep warm. The most satisfactory covering is one pair of heavy, soft woolen socks, over which is placed one pair of thermolyte (heavy pliable plastic) socks. The rubber feet of the swim suit make the third and outer covering. Clad thus, feet retain warmth at 30°-40°F temperatures for thirty to sixty minutes. The most satisfactory head covering is a hood of polyvinylchloride material, worn under the swim suit. This will keep a diver comfortable for about sixty minutes in 35° water. With a face mask covering eyes and nose, only the mouth and lips are exposed. No excessive discomfort was found in the oral areas, even when ice formed on the head piece.
Extracts from the log of an Underwater Demolition Team operating off Kodiak, Alaska, January, 1948, are of interest:
“a. The reconnaissance was conducted by twenty-six swimmers. The water temperature was 36°F. Slush and ice was encountered near the beach which probably lowered the temperature three to five degrees.
“b. The average time spent in the water was fifty-five minutes with the maximum one hour fifty minutes and the minimum twenty minutes. The swimmers covered distances of one-half to 1¼ miles.
“c. The average body temperature of swimmers returning to the ship was 93° with an average time of thirty minutes being required for temperatures to return to normal. This was aided by supervised shower baths, starting with cold water increasing to room temperature, about 70°F. All swimmers suffered from chilling of the hands and feet.
“d. During the entire operation in Arctic waters, five members contracted colds, four of these did not participate in the three months of physical and swim training conducted at San Diego, California, prior to departure.”
The data on the following page was recorded during various expeditions to the Arctic.
In addition to the above records, many dives have been made in polar waters in depths to sixty feet and water temperatures of 28°-40°F. In all cases experience proved that divers could endure extreme cold temperatures if adequately equipped. In diving operations conducted under adverse conditions, there are apt to be psychological problems. In a group of men with the high morale, competitive urge, and the team spirit of UDT there is no such problem. Well trained men desire to dive and meet the challenge of a tough assignment. There are hazards in all diving operations, and the onset of diver’s disease is heightened by the cold. Some hazards are unique to the Arctic environment. In Cambridge Bay, Canadian Northwest Territories, during the survey of the Dew Line, the ice started to break up in July. Two officers, Lieutenant Charles Aquadro, MC, USNR, and Lieutenant (jg) Alan Jones, USNR, of UDT were apparently struck with spring fever one Sunday and started to swim across the bay toward an Eskimo camp. They were clad in black exposure suits, rubber gloves, and large swim fins. Alternately crawling over ice floes and swimming through the water, they neared shore. The sled dogs started howling. Eskimo hunters, who had never seen a man swimming, came out of their tents and, on seeing the figures, rushed for their high-powered rifles. The UDT men had been mistaken for seals, the favorite food of the Eskimo and husky. Only wild cries and frantic gestures prevented a fusillade.
We have read much concerning the beauties of diving in tropical waters, amid gorgeous-hued corals, friendly fish, the “raptures of the deep,” the profound glory of the silent world bathed in beautiful sunlight, and other romantic platitudes. Such joys will not be encountered in polar waters. My acclaim and admiration go to the divers who, in daily pursuit of their hazardous trade, descend into the cold gloom of turbid waters where the light of sun is seldom noticed and the hand cannot be seen in front of the face—where the diver crawls through mud,' enters jagged wrecks, wrestles with snaky coils of air and communication lines, and expends his strength in handling cumbersome tools and forcing rusted fittings—-where he feels the terror of a sudden cut-off of air supply, or the dread of entrapment. To the military divers of World War II and the Korean War—the British, American, and the gallant Italian and German divers, who swam in mined waters carrying large demolition charges, who suffered long hours in the dark and cold, who felt the concussion of charges detonated with the intent to destroy them, and yet carried on—to these men should go the applause and recognition. The knowledge and experience gained from such divers as these makes the task of entering polar waters a relatively simple one for today’s skin divers.
Man is rapidly becoming acclimated to life under the sea, his ancestral home. He is able to plumb its deepest depths while enclosed in submersible and bathysphere. With artificial lungs and the equivalent of blubber, hair and hide on his body, he can join the seal, the walrus and the polar bear in and under the limitless ice of the polar seas.