Figure 3. Fixed continental shelf laboratory. 
Figure 4. Diver adjusting tow line on sea plow 
used to bury undersea cables below ocean floor. 
Presence of man on the continental shelf is 
necessary for conduct of many operations. 
Divers will also be useful in resource recovery 
operations, which will become increasingly im- 
portant as terrestrial sources are depleted. 
(American Telephone & Telegraph photo) 
VI-226 
