ZooBlog

True seals
Harbor seals are members of the true seal family, and since true seals have lived in aquatic lifestyle for so long, they are just not very graceful on land. Their hind flippers may not be that much used to them on land, but they are in the water. They use them in a side-to-side motion called sculling. Sculling might looks just a little bit silly to you and me, but it is an adaptation that works well for their ancestors, and that is a nature's design.

From the Wildlife Conservation Society:
"While most northern seals are associated with ice, harbor seals are instead mostly found along shorelines and in estuaries. Harbor seal numbers declined for a time in New York area waters due to pollution, but the population around Long Island is growing again, possibly because of cleaner coastal waters."

Animal Info
Atlantic harbor seals can be seen at the New York Aquarium and Central Park Zoo.