Grey seal pups have a white coat and rather petite figure, much unlike their grey and, ahem, voluptuous parents. This doesn't last for long, however. Seal pups are fed milk from their mothers that is 60-percent fat, and these pups can quadruple in size in the first three weeks after birth! This insulating layer of blubber helps protect the seal from cold. In fact, full-grown seals can dive to a depth of about 300 meters in subarctic waters.