Seals Sleep As They Sink in the Sea (LiveScience.com via Yahoo! News)
When northern elephant seals (Mirounga angustirostris) migrate between their breeding and foraging grounds, they spend as long as eight months at a time at sea. They're almost always underwater, devoting only a few minutes to breathing at the surface between dives-hardly long enough for a nap. After a sip of air, they often sink quickly to 500 feet, then drift farther down in a shallow descent ...