During summer the polar bear rarely visits shore, but in winter commonly extends its wanderings to the Arctic islands and the bordering mainland coasts. In winter it ranges southward with the extension of the ice pack. In spring, by an unexpectedly sudden retreat of the ice, individual bears are often left south of their usual summer haunts, sometimes being found swimming in the open sea far off the coast of Labrador. Occasionally some of those which migrate southward with the ice through Bering Straits fail to turn north early enough and are stranded on islands in Bering Sea. That a carnivore requiring so much food as the polar bear can maintain itself on the frozen polar sea is one of the marvels of adaptation to environment. The activity of these bears through the long black night of the far north is proved by records of Arctic explorers, whose caches have been destroyed and ships visited by them during that season. In this period of privation they range far over land and ice in search of food, and when in desperate need do not hesitate to attack men. I have seen several Eskimos who had been seriously injured in such encounters, and learned of other instances along the Arctic coast of Alaska in which hunters had been killed on the sea ice in winter. During the summer season of plenty, polar bears are mild and inoffensive, so far as men are concerned. At that time they wander over the pack ice, swimming in open leads, and, when hungry, killing a seal or young walrus. When spring opens, many polar bears are near the Arctic coast. At that time the natives along the northeast coast of Siberia kill many of them on the ice with dogs and short-hafted, long-bladed lances. The dogs bring the bear to bay, and the hunter, watching his opportunity, runs in and thrusts the lance through its heart. During the cruise of the _Corwin_ we saw many of these bears on the broken ice off Herald and Wrangel Islands. One large old male climbed to the top of an uptilted ice-pan and, after looking about, lay down on one side and, giving a push with one hind foot, slid down head foremost 30 or 40 feet, striking the water with a great splash. He then climbed out and walked sedately away. Another bear saw a seal basking on the ice by a large patch of open water and, swimming across, suddenly raised himself half out of the water to the edge of the ice, and by a blow of his paw crushed the seal’s skull. He then climbed out and made a feast within 500 yards of where the _Corwin_ was anchored to the ice pack. Once while we were anchored in a dense fog several miles off the pack a bear came swimming out to us, stopping every now and then to raise its head high out of water to sniff the attractive odors from the ship. Although strong and tireless swimmers, these bears lack the necessary speed to capture their prey in the water.