Males are slightly larger than females.
They are true, or crawling seals, having no external earflaps. True seals also have small flippers, and must move on land by flopping along on their bellies. Harbor seals are found across the Northern Hemisphere in both the Atlantic and Pacific Oceans. In the northeast Pacific, they range from Alaska to Baja California, in Mexico. They favor near-shore coastal waters and frequent sandy beaches, mudflats, bays, and estuaries.