The southern elephant seal is the world’s largest seal. It is a heavy-built, long-body seal with proportionately small flippers and some skin folds just behind the head. The dark eyes are large and round. The adults have short stiff hair, usually dark grey dorsally and paler ventrally. Males have squarer and larger heads, with a conspicuous proboscis, while females have more rounded heads with no proboscis. Breeding males may weigh up to a sixth that of a breeding female. Males can grow to 4.5-6.5 metres and 3,700 kg; females can grow to 2.5-4 metres and between 360-800 kg.