Narwhals live in Arctic waters. In summer, Narwhals tend to occupy protected, deepwater coastal areas for either calving or feeding opportunities. In the fall and winter, they favour waters that range in depth from 1,000 to 5,000 m. Overall, the quality of the ice habitats, especially areas of open water and the density of pack ice, seems to be a key aspect of habitat selection.

Narwhals, also known as sea unicorns, are toothed whales. They are medium-sized whales with no dorsal fin. Newborns are grey or bluish grey and change to black after weaning; with age, white streaks develop on the underside and flanks. Adults are white to creamy yellow on the belly and grey-black on the back. The very old, especially males, are almost completely white. Adults have only two teeth. In most males, the right tooth remains embedded in the skull; the left forms a spiral tusk that can extend over 3 m. Females with a tusk, males with no tusk, and two tusks are rare occurrences. Newborns weigh about 80 kg and are 1.6 m long. Adult males can reach 5.4 m in length and about 1,935 kg in weight; females 4.9 m and about 1,552 kg.