The gold medal for deep diving goes to a bull southern elephant seal, recorded at an incredible 2,388m, says Ellen Husain. While this is extreme, the species frequently dives to depths of 400–800m, staying under for 20–30 minutes.
Motivated by food, elephant seals plumb the depths for squid and rays, often at nutrient-rich boundary zones where different oceanic waterbodies meet.
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Since it takes time to get down, hunt and resurface, these seals have astounding breath-holding abilities – up to two hours is known. They can carry three times more oxygen in their blood than humans, also storing it in their tissues.
So the precious oxygen lasts even longer, the seals lower their heart rate to slow the pace at which it is used, and are able to tolerate very low levels of blood oxygen at the end of dives.
