The fact that most images of polar bears show them on land or ice says more about the practical difficulties faced by humans than it does about the bears’ behavior. With adaptations such as thick blubber and nostrils that close, polar bears are, in fact, highly aquatic, and they spend most of their time hunting seals on sea ice and are capable of swimming for hours at a time. Paul took his Zodiac boat to Hudson Bay, Canada, in midsummer to rectify this bias. He scouted for three days before he spotted a bear, this young female, on sea ice some 30 miles offshore. ‘I approached her very, very slowly,’ he says, ‘and then drifted. It was a cat-and-mouse game.’ When the bear slipped into the water, he just waited. ‘There was just a flat, world of water and ice and this polar bear swimming lazily around me. I could hear her slow, regular breathing as she watched me below the surface or the exhalation as she surfaced, increasingly curious. It was very special.’ The light was also special, but for a sinister reason. The midnight sun was filtered through smoke from forest fires raging farther south, a symptom of the warming Arctic – the greatest threat facing the polar bear. As more and more sea ice melts earlier and earlier every spring, it becomes harder for the bears to hunt the seals they depend on.