A fatty tissue called "blubber" keeps them warm. The harbor seal, also known as the common sealis a species of a seal. Females outlive males (30-35 years versus 20-25 years). Most harbor seal pups shed a white wooly coat before they are born. Harbor seals are the seals with the largest geographical range, they are found in coastal waters of the northern Atlanticand PacificOceans and the Balticand NorthSeas. The harbor seal can plunge 300 feet and stay underwater up to 28 minutes.