At about 1.5 m (5 ft.) long and 68 kg (42 lb.), the ringed seal is the smallest seal. It is the most common seal in the Arctic, and it is found wherever there is open water in the land-fast ice.

Pups are born with white coats, which camouflages them against their snow and ice habitat. The ringed seal has the ability to make birth lairs in drifted-over, broken ice to protect the young from cold, while allowing easy access to seawater through holes. They can make and maintain a series of breathing holes in ice up to 2 m (6.5 ft.) thick. They also use the holes for escape from predators—especially the polar bear.

Several ringed seal fossils are known from northern North America. A bone from Malaspina, Alaska, may represent an early invasion of this kind of seal into the Arctic Ocean about 3 million years ago. Such seals lived north of Teschekpuk Lake, Alaska and near Thule, Greenland during the last interglacial (about 130 000 years ago). They also lived along the coasts of Prince of Wales Island, Alaska, from about 24 000 to 14 000 years ago. The oldest radiocarbon-dated specimen has an age of about 42 000 years ago from Banks Island, Northwest Territories.

Some 11 000 years ago, ringed seals lived much farther south near Ottawa, Ontario, in the western part of the Champlain Sea. (This sea was an arm of the Atlantic Ocean that covered the St. Lawrence Lowlands just after the ice sheet had melted back northward). Indeed, a nearly complete skeleton of this species was found in marine clay in what is now Gatineau, Quebec.

Because of our knowledge of living ringed seals we can tell a lot about conditions in the vanished Champlain Sea. Palaeontologists conclude that, since they give birth to their pups on land-fast ice in spring, such conditions existed near Ottawa 11 000 years ago. Several other ringed seal fossils have been found in Champlain Sea sediments near Ottawa. Remains of small clams found with the skeleton indicate the seawater was cool and very salty—conditions that exist now in the ringed seal's Arctic habitat.