The harbor seal the most common species by far on the Northeast coast is built like a torpedo, with powerful hind flippers that propel it through the water at remarkable speeds, and down to depths as great as 200 fathoms. The cold water would be as dangerous to a seal as to a human were it not for the seal's blubber layer, which provides insulation, a fat reserve, and buoyancy all in one thick blanket. Seal Socialization In summer, harbor seals can be found from New Hampshire and southern Maine north to the edge of the Arctic ice, and they are a common sight among the lobster buoys of the New England coast. Even in summer they are somewhat social, gathering in small groups on offshore ledges exposed by the falling tide, but in winter they may congregate in much greater numbers. One of the largest gatherings of harbor seals in the United States occurs late each winter along North and South Monomoy Island, south of Cape Cod's elbow up to three thousand seals, loafing and feeding as they wait for spring.
Individuals vary widely, however, from dark brown to bleached blonde.
Sapien Fish make up most of a harbor seal's diet, and that has long brought them into conflict with people. Federal protection has brought an increase in seal numbers, and although they no longer breed in much of their southern range, there is hope that they may recolonize those areas as well. A growing problem is human harassment much of it unintentional from recreational boaters such as sea kayakers. This harassment forces breeding seals into marginal calving sites where they are more exposed to storms and predators such as sharks. As the nickname suggests, the shape of the head is the main distinguishing characteristic.