Ringed seals stay close to drifting pack ice or shorefast ice for most of the year, and much of their time is spent swimming beneath it. They are great divers and can stay under water for up to 30 minutes.

But, as air-breathing mammals, they must always have a way to get back to the air, or else they will drown.

In autumn and early winter, openings in the ice start freezing over, so the seals create breathing holes. They keep the holes open with their strong claws, and by pushing their noses through the new layers of ice.

This makes seals very vulnerable. When there's no open water nearby, they have no choice but to stick their heads up through the little holes.

Both polar bears and hunters know this. They look for the breathing holes, and wait patiently until the seal needs to come up for air.

For the seals, it's like playing "Russian roulette". If they pop their head up through the wrong hole, they could be facing a spear, a rifle, or sharp teeth and claws. When a seal goes up for a "breather" - it could be taking its last breath!