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.
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Despite weighing up to 4 tonnes, this mammal can dive to depths of 2000 metres, hold its breath for an incredible two hours and even control its heart rate
