Narwhals inhabit vast areas of Arctic waters.
In the summer, Narwhals prefer to swim in deep coastal waters that offer shelter from the wind. During spring and fall migrations, and while wintering in the Arctic pack ice, narwhals tend to prefer deep fjords and the continental slope. Upwelling in these deep waters may provide essential nutrients to support larger populations of typical narwhal prey species. The quality and density of pack ice is also considered significant in the narwhals' choice of habitats.
There are three known populations of narwhals. Two of them, one identified with Baffin Bay and the other with Hudson Bay, are found in Canadian waters. The third population of narwhals is identified with the waters east of Greenland. These identifications are somewhat tentative and do not take into account any interchange that may occur between the groups. Further study may also reveal distinct groups within those currently recognized.
The Hudson Bay population is believed to range over an area of approximately 96,500 square miles (250,000 square kilometres).