More than their appearance is remarkable about elephant seals. They can dive as deep as a mile, where the pressure is crushing, and stay underwater for as long as two hours. Even if their muscles do store oxygen and their spleens act as scuba tanks, squeezing oxygen into the blood stream as needed (as do the spleens of race horses), scientists can explain only 50 minutes of two-hour dive.

The research has implications for human divers and for several areas of medicine: reducing surgical trauma, controlling heart arrhythmias, and such oxygen-deprivation situations as children submerged in icy water (they sometimes survive 30-minute immersions) and sudden infant death syndrome, which may have to do with breathing interruptions.