The two subspecies occur in geographically isolated populations. Several populations of Atlantic walrus occur in Canada and Greenland, while the Pacific walrus is represented by a single stock of animals which inhabits the Bering and Chukchi seas. Pacific walruses are one of the largest pinnipeds. The head in both sexes is characterized by a pair of enlarged upper canine teeth that project downward as tusks, small eyes, a lack of external ears, dorsally situated nostrils, and a squarish snout with hundreds of stiff mystacial vibrissae. The head and body are covered with short, tawny hair but the flippers are bare.
Walruses are dark when they are young and become progressively lighter with age.
Immersion in cold water causes a restriction of blood flow to the skin and a pale, almost white appearance. The Pacific walrus mainly inhabits the shallow continental shelf waters of the Bering and Chukchi seas. The distribution of Pacific walruses varies markedly with the seasons. Virtually the entire population occupies the pack ice in the Bering Sea in the winter months. Through the winter they generally congregate in two areas, one immediately southwest of St. Lawrence Island and the other in outer Bristol Bay.