The scientists, based at Woods Hole Oceanographic Institution in Massachusetts, USA, were following the movements of beaked whales, dives of which easily exceeded the deepest dives previously recorded – by sperm whales to some 1200m.

The dives, said the Woods Hole team, represented the 'deepest confirmed dives reported from any air-breathing mammal'.

Meanwhile, scientists in Norway have established that another air-breathing underwater mammal, the hooded seal, manages to dive deep by allowing its body to go into an almost hypothermic state, so slowing metabolism and conserving on oxygen consumption.

The team, from the University of Tromso, observed hooded seals diving to 1000m, during which they managed to turn off the body's natural shivering process, which is designed to create heat.

?