Tagging work off southern California recorded a Cuvier's beaked whale dive to a depth of about 2,992 metres, the deepest confirmed for any mammal. A later study from the same research programme documented an individual submerged for more than three hours, with the longest recorded dive around 222 minutes.
These numbers exceed the aerobic dive limit calculated from the species' body oxygen stores by a wide margin, which means the animal must be running substantially on anaerobic metabolism, tolerating lactate accumulation that would incapacitate most mammals. Beaked whales also carry adaptations shared across deep divers: collapsible lungs, high myoglobin concentrations in muscle, and profound bradycardia with blood shunted away from non-essential tissue.
The extreme records may not represent normal behaviour. The very long dives were recorded from animals in an area with naval sonar activity, and disturbance is one candidate explanation for unusually extended submergence. Typical foraging dives for the species are much shorter, generally under an hour.