4.11. MAN IN THE SEA 
Marine construction and maintenance operations in 1966 require 
free divers. The opinion of oil company staffs is that free divers will 
continue to be used where they can be put down and provided with 
tools to do useful work. Since oil and mining companies expect by 
1975 that some operations will be conducted at depths byeond 1,500 
feet, there will be a transition from divers to unmanned vehicles or 
manned instrumental platforms. 
Oil industry needs clearly show many potential uses for man in the 
sea. Other users have requirements that demand a capability for 
men to live and work beneath the surface for extended periods. This 
capability may lead to new opportunities in the production of food 
either by fishing or aquiculture. Further, the interest of national 
security may make it necessary or strategically desirable to occupy 
areas of the oceans for extended periods. 
Major groups of problems are associated with man living and work- 
ing beneath the surface of the sea: 
1. Problems directly related to survival, including biomedical 
problems and hazards from marine organisms. 
2. Problems associated with design and operation of facilities 
for working while underwater. Certain of these problems have 
been considered earlier in this report. 
Biomedical problems of survival are divisible into several categories. 
Most immediate are those produced directly by the wet, cold, dark, 
high-pressure climate. These include but are not restricted to an 
increased resistance to breathing during exertion and at rest; central 
nervous system narcosis by nitrogen and probably any other inert 
gas; long, slow decompression necessary for safe elimination of ex- 
cessive inert gas from the tissues; toxicity of oxygen at high pressure; 
loss of body heat during prolonged submergence; and complex inter- 
actions of these factors. As the duration of man’s underwater stay 
increases, additional problems appear. These include man’s nutri- 
tional requirements under these rigorous conditions, composition and 
palatability of foods, psychological behavior of isolation and crowd- 
ing in small spaces, and impairment of speech by unusual atmospheres. 
Medical procedures, including action of drugs on man in the sea, also 
require study. The similarity of certain of these problems to manned 
spaceflight is obvious, and advantage should be taken of this fact. 
The presence of other sea organisms constitutes yet another group 
of complications. In many marine environments a variety of orga- 
nisms are toxic if touched or eaten. Also, predatory forms such as 
sharks consider divers fair game. 
Human survival underwater thus requires solution of a multiplicity 
of problems. Current knowledge in most of these areas is at best 
27 
