Harbor Seal Harbor Seals often arrive in Block Island waters as early as late November and depart about mid-April. Some of the best views of Harbor seals around Block Island can be had when they are hauled out: on rocks near Old Harbor point, on floating docks in Cormorant Cove, or on the beach below Clay Head. Care must be taken to limit your length and proximity of observations so that the seals do not become stressed and harassed. Harbor seals are the most abundant seal seen in Block Island waters*, and over the past 15 years winter counts have shown a great increase. In Block Island waters, the primary food of Harbor seals is: fish such as flounder, herring and cod, shellfish and squid. Harbor seals are 4 - 6 feet in length and weight up to 250 pounds. (Females are about 20% smaller). In winter months, Harbor seals migrate from northern New England and Canada to southern New England, and as far south as the Carolinas. Harbor seals can swim up to 11 mph, and dive 300 feet. Harbor seals haul out at low tide (often on the same favorite rocks and beaches) to rest, sleep, save energy, and regulate body temperature. They will also haul out to give birth and nurse their young. *In addition to Harbor seals, Gray seals, Harp seals and Hooded seals can also be seen around Block Island. View All "Critters of Block Island" Ocean View Foundation Connecting People and Nature