They remain open throughout the winter months. In addition to surfacing at leads and polynyas, seals cut breathing holes in the ice. The Inuit call these holes aglus. In fall, each seal cuts ten to fifteen aglus in the ice, using the sharp claws on their foreflippers. They keep the aglus open throughout the winter, even when the ice is six feet deep.
Seals swim to the surface to breathe every five to fifteen minute.
But because they visit as many as fifteen breathing holes, a polar bear's wait for its prey can be long. Polar bears locate breathing holes with their powerful sense of smell. Polar bears depend on the presence of ice for access to seals. In summer, when the floes retreat north, polar bears will travel hundreds of miles to maintain contact with their prey. Between summer and winter the amount of ice-covered water can change rapidly.