Average Hawaiian Monk Seal Size
Hawaiian monk seals are one of the largest true seals in the world. Adults typically measure 2.1 to 2.3 meters (7 to 7.5 feet) in length and weigh between 170 and 230 kilograms (375 to 500 pounds). Males are usually slightly smaller than females.
Pup Size and Growth
Newborn pups are about 0.9 to 1.1 meters (3 to 3.5 feet) long and weigh around 16 to 18 kilograms (35 to 40 pounds). They grow quickly on rich milk, often doubling their weight within the first month before weaning.
Comparing Size to Other Seals
Compared to harbor seals, Hawaiian monk seals are notably larger and more robust. Their size helps them conserve heat in cooler deep-water foraging dives. For detailed measurements and conservation context, see the NOAA Fisheries Hawaiian monk seal overview.
