Cuvier's beaked whales routinely dive beyond 1,000 metres for around an hour to hunt squid, spending the interval between dives at shallow depths. The two exceptional records come from opposite coasts of North America. Tags deployed off southern California logged a maximum depth of 2,992 metres, and a separate tagging programme off Cape Hatteras, North Carolina, recorded a single dive lasting 222 minutes.
The physiology is stretched but explicable. Beaked whales collapse the lungs early in descent, store most of their oxygen in blood and muscle rather than in air, carry very high myoglobin concentrations, and slow the heart drastically. The longest dives are outliers rather than routine: the two longest on record came from one tagged animal, following naval sonar activity that may have altered its behaviour.
The species is also the one most frequently linked to mass strandings during naval sonar exercises. The association is well documented in the Mediterranean and elsewhere, though the physiological pathway from sound exposure to death is still argued over.