The gold medal in deep diving goes to a southern elephant seal, recorded at an incredible height of 2,388m, says Ellen Husain. While this is extreme, the species frequently dives to depths of 400 to 800 m, remaining underwater for 20 to 30 minutes. Motivated by food, elephant seals explore the depths in search of squid and rays, often in nutrient-rich border zones where different ocean bodies of water meet. Since it takes time to descend, hunt, and resurface, these seals have an amazing ability to hold their breath; It is known that they can last up to two hours. They can carry three times more oxygen in their blood than humans, also storing it in their tissues. To make precious oxygen last even longer, seals reduce their heart rate to slow the rate at which they use it and are able to tolerate very low blood oxygen levels at the end of dives.
