departure from mixed gas breathing, opens the 
possibility of greatly shortened decompression 
periods. 
Needs in breathing gas technology include: 
—New breathing mixture components that provide 
chemical inertness and nontoxicity without unde- 
sirable changes in density and thermal conductivity. 
—Better understanding of the toxic reactions of 
oxygen, carbon dioxide, nitrogen, and hydrogen. 
—Better understanding of the effects of various gas 
mixtures—one component on another. 
—Data on the physical aspects of respiration under 
water during various levels of physical activity. 
—Better understanding of the aeroembolism pro- 
cesses (blood and tissue gas dynamics) and subse- 
quent establishment of more precise decompres- 
sion procedures. 
—Toxicity of oxygen at high pressure and _pro- 
longed exposures. 
—Central nervous system narcosis by nitrogen and 
other inert gases. 
Closely related is the need for bio-engineering 
development to solve the problems of: 
—Equipment and materials to maintain body heat 
balance and to preserve tactile sense and manual 
dexterity. 
—Increased resistance to breathing under increased 
pressures. 
—Long, slow decompression. 
—Loss of body heat during prolonged submer- 
gence. 
—Impairment of speech by artificial atmospheres. 
—Action of drugs and medical procedures for man 
in the sea. 
Effective, compact, and compatible swimmer 
doppler navigation and sonar systems are needed. 
Today’s support equipment is too heavy, bulky, 
and difficult to integrate into the total diver 
system. 
There is an urgent demand for breathing appa- 
ratus using available breathing gases most effi- 
ciently and for a system to heat diving suits under 
deep sea pressures and temperatures. 
3. Conclusions 
Current diving technology permits operations in 
protected or relatively shallow waters to a depth 
of approximately 600 feet; however, free diving in 
excess of 1,200 feet will probably soon be 
realized. With proper emphasis, this capability 
probably can be increased to 2,000 feet or more, 
but there are extremely difficult physiological 
hurdles to be overcome in diving at much greater 
depths. 
Progress of free diving at greater depths is 
retarded by such numerous problems as safety, 
breathing gases, body heat retention, diver speech, 
and decompression. Research and development is 
in progress on these matters. Liquid breathing 
research, if successful, may provide a means of 
attaining depths in excess of 2,000 feet. 
Oxygen toxicities and hypoxia have been exten- 
sively studied, but long-term exposure to such 
inert gas mixtures as helium-oxygen, nitrogen- 
oxygen, or hydrogen-oxygen mixtures at pressure 
has not been studied sufficiently to establish 
appropriate diver exposure limits. Reduction in 
decompression time for saturation divers is ex- 
pected to become a critical economic factor in 
utilization of free divers. 
In engineering designs of diver support equip- 
ment, specialized problems are involved and off- 
the-shelf techniques should be used with discrimi- 
nation. 
The number of deep ocean divers is multiplying 
on all coasts, and saturation diving will become 
common practice in the near future. There is a 
shortage of sustained funding for personnel and 
facilities engaged in advanced diving research and 
medical treatment. 
Recommendations: 
Research should be pursued to make possible 
effective free diving at depths of 2,000 feet in 10 
years or less, seeking to attain increased depth 
capabilities in 20 years by perfection of liquid 
breathing. 
Research and development should be acceler- 
ated to improve and simplify diving techniques, 
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