Baffin Bay, located between Baffin Island and the west coast of Greenland, is defined by the International Hydrographic Organization as a marginal sea of the Arctic Ocean.: Art.23 It is sometimes considered a sea of North Atlantic Ocean. It is connected to the Atlantic via Davis Strait and the Labrador Sea. The narrower Nares Strait connects Baffin Bay with the Arctic Ocean. The bay is not navigable most of the year because of the ice cover and high density of floating ice and icebergs in the open areas. However, a polynya of about 80,000 km2 (31,000 sq mi), known as the North Water, opens in summer on the north near Smith Sound. Most of the aquatic life of the bay is concentrated near that region.
The North Water provides air to ice algae and zooplankton and is characterized by abundant fauna. Of about 20,000 beluga whales living in the Baffin Bay, some 15,000 are concentrated at the North Water. Other abundant animals of the region include walrus, narwhal, harp seal, bearded seal, ringed seal, bowhead whale, rorquals and polar bear. All aquatic mammals crucially depend on the availability of open water; they have very limited ability to maintain breathing holes in ice and are all vulnerable to attacks by the polar bear when breathing at the holes. The seals and walrus occupy areas of fast ice, which is essential for giving birth and raising the pups. Bearded seals feed near the bottom of the bay and therefore are restricted to the shallow waters. Ringed seal is the most common meal of the polar bear. It is also an occasional prey of the walrus and Arctic fox. Most large animals of the bay are being traditionally hunted, but the hunting has been restricted in the 20th century in order to preserve the wildlife population. For example, the quota for polar bears in the bay area is 105 per year.
There are about 400 plant and tree species on the bay shores, including birch, willow, alder and plants adapted to salty soils, as well as lyme grass, mosses, and lichens. These serve as food for caribou and rodents, such as lemming. Resident fish species include polar cod, Arctic flounder (Pleuronectidae, Liopsetta), four-horned sculpin and capelin, whereas cod, haddock, herring, halibut, and rattail migrate from the Atlantic. The birds are represented by the little auk, snowy owl, willow ptarmigan, rock ptarmigan, gyrfalcon, Arctic redpoll and guillemots. Most of them migrate to the south during the winter.