Photostory #99: Canadian Experts Clear Arctic Waters: Divers Ensure DEW Line Supply
National Film Board of Canada
April 2, 1957
Canadian Museum of Contemporary Photography fonds, National Gallery of Canada Library and Archives
Naval "frogman" Lieut.-Cdr. Ben Ackerman of Peterborough, Ont., checks his gear. This "free-diving" suit allows much greater mobility since the diver carries his air supply with him. The bottles contain oxygen and nitrogen, mixed in the required proportions according to the depth of the dive. Consumption of oxygen varies with water conditions and depth of the dive. In a 100-foot dive, bottles offer total endurance of 85 minutes.