Career
Zetterström first described the use of hydrogen as a breathing gas in 1943. From 1943 to 1944, a total of six ocean dives were made utilizing this mixture with the deepest to 160 meters (96% hydrogen and 4% oxygen). On 7 August 1945, Zetterström experienced technical problems diving from the HMS Belos.
His support divers misread his signals and this was followed by a rapid ascent that resulted in severe decompression sickness and hypoxia.
