Claim: Human physiology of underwater diving shows a human has only 20ml/kg oxygen stores allowing him a maximum depth of 133 meters, as compared to a mammalian elephant seal, which has 97ml/kg stores allowing a maximum depth of 1500 m.
Evidence: Elephant seals stay at sea for between 2 and 8 months and dive continuously, spending 90% of their time underwater and averaging 20 minutes per dive with less than 3 minutes at the surface between dives. Their maximum dive duration is about 2 hours and they routinely feed at depths between 300 amd 600 m, though they can exceed depths of 1600 m. Beaked whales have been found to routinely dive to forage at depths between 835 and 1070 m, and remain submerged for about 50 minutes.