The sea lion of New Zealand's sub-Antarctic, Hooker's sea lion Phocarctos hookeri, was named after the botanist of Ross's naval survey expedition which first brought specimens back for scientific study. This animal breeds in large colonies at Carnley Harbour and Enderby Island, in the Auckland Islands group. A few breed on Campbell Island, and larger groups of non-breeding adults are reported from the Snares and other sub-Antarctic islands. Sea lions are generally larger and heavier than fur seals; large males measure up to 10 ft and have a characteristic “mane”; mature females range from 5 to 7 ft in length. They lack the dense underpelt which fur seals have; their hide was, however, tanned and used as a strong, supple leather for clothing. Hooker's sea lion is grey or fawn, fading to white; the species is peculiar to the New Zealand area, although closely related to similar animals on other islands in the southern oceans. Little is known of its habits or numbers.

Elephant seals or sea elephants (so called from the large, inflatable proboscis of the males during the breeding season) are found throughout the sub-Antarctic islands of the Atlantic, Indian, and Pacific Oceans. In the New Zealand region they breed in large concentrations on Campbell and Macquarie Islands, and in 1949 a small breeding colony was reported to have formed on the Antipodes Islands. The largest bulls of this species reach lengths of 20 ft or more; cows are seldom longer than 10 ft. The hair is coarse and short. Old bulls are often heavily scarred from fighting and lose much of the hair from their neck and face. Their colour is buff or brown, but may vary from silver grey to fawn in younger animals; cows and young bulls are similar in shape and colour, and the distinctive inflatable proboscis of the mature bull appears only in the sixth or seventh year. Like all other Phocids, elephant seals lack external ears. Their hind limbs trail backward both in walking and in swimming; the forelimbs are reduced in comparison with those of the Otariidae, and the animals move by undulating the muscles of the trunk. The species has recently been made the subject of an intensive study by Australian biologists on Macquarie Island (see papers by Carrick and others in CSIRO Wildlife Research 7 (2), 1962).