Okene was trapped in a capsized boat with an air bubble described as only 4 feet high. Normally, a person would need about 1,000 cubic feet of atmospheric air to survive 60 hours. At a depth of 100 feet, this volume would be compressed by a factor of about 4 by the water pressure, so theoretically an air pocket with dimensions 6x6x6 feet would contain enough oxygen to survive for that time.
It’s not the lack of oxygen but poisoning by the exhaled carbon dioxide that would first kill the person in this situation. However, the physics of interaction of atmospheric gases with water could make a critical difference in this case. Carbon dioxide is very soluble in water (much more so than nitrogen and oxygen), and its absorption by the water could have been the reason why carbon dioxide did not build up to the lethal concentration of about 5 percent.
“This man was lucky to survive mainly because a sufficiently large amount of trapped air was in his air pocket,” Umansky said. “He was not poisoned by the CO2 after 60 hours spent there, because it stayed at safe levels, and we can speculate that it was helped by the ocean water sealing his enclosure.”