Which bird holds the record for the deepest dive of any bird?

The emperor penguin holds the record for the deepest dive of any bird.

Emperor penguins usually forage between 150 and 250 metres below the Southern Ocean’s surface, but electronic time-depth recorders have documented much deeper dives. One reached about 564–565 metres, deeper than any other reliably recorded bird dive.

This ability is supported by several adaptations. Emperor penguins carry large oxygen reserves in their blood and muscles, can slow their heart rate dramatically underwater, and reduce oxygen use by nonessential organs. Their streamlined bodies and powerful flippers also make them efficient swimmers.

The record is easy to confuse with dive duration: emperor penguins also hold the bird record for the longest recorded underwater dive, at 32.2 minutes. Thick-billed murres and king penguins are impressive divers too, but neither approaches the emperor penguin’s documented maximum depth.