The grayish skin of the walrus is 2–4 cm (1–2 inches) thick, with deep folds around the shoulders. The skin is covered with short reddish hair, giving the animals an overall cinnamon colour. The walrus has a rounded head, small eyes, and no external ears. Its muzzle is short and broad and has a conspicuous moustache of stiff, quill-like whiskers (vibrissae). The male, which reaches a maximum length and weight of about 3.7 metres (12 feet) and 1,700 kg (3,700 pounds), is about a third larger than the female.

The walrus is a gregarious animal, living in groups sometimes numbering 100 or more. It does not frequent deep water, instead inhabiting coasts and margins of ice shelves, where it periodically hauls itself onto beaches and ice floes to rest and bask. Like the sea lion and fur seal (family Otariidae), the walrus can turn its hind flippers forward under its body when on land and can thus crawl using all four limbs. Males mate with multiple females in winter. Dominance is established among males according to body and tusk size. They display by showing their tusks and making clicking and bell-like sounds underwater. When a female is attracted, she joins the male, and mating occurs underwater. Delayed implantation of the fertilized egg results in a total gestation of 15–16 months. The single walrus pup weighs about 60 kg (130 pounds) at birth and remains with the female for two to three years. Sexual maturity occurs at six to seven years of age in females, eight to ten years in males. In the wild, walrus can live slightly more than 40 years. On rare occasions they are killed by polar bears or killer whales.

The walrus is valued by both the and commercial hunters for blubber, hide, and ivory tusks. Its numbers have been reduced by commercial operations. Walrus are now protected from sealers but are still subject to subsistence hunting by aboriginals. Like seals, the walrus is a pinniped. It is the sole living member of the family Odobenidae.