It is a medium-sized goose, 60–75 cm long, the wingspan 135–170 cm, and weighing 1.8–3.3 kg. It has a short bill, bright pink in the middle with a black base and tip, and pink feet. The body is mid grey-brown, the head and neck a richer, darker brown, the rump and vent white, and the tail grey with a broad white tip. The upper wing-coverts are of a somewhat similar pale bluish-grey as in the Greylag Goose, and the flight feathers blackish-grey. The species is most closely related to the Bean Goose, sharing a similar black-and-coloured pattern bill, but differing in having pink on the bill and legs where the Bean Goose is orange, and in the paler, greyer plumage tones. It produces a medley of high-pitched honking calls, being particularly vocal in flight, with large skeins being almost deafening.
Nesting is often on cliffs close to glaciers to provide protection from mammalian predators, also on islets in lakes. Three to six eggs are laid in early to mid May in Iceland, late May in Svalbard, with incubation lasting 26–27 days. On hatching, the goslings accompany the parents on foot to the learest lake, where they fledge after about 56 days. Southbound migration is from mid September to early October, and northbound from mid April to early May.
The diet is almost entirely vegetarian. In summer, they feed on a wide range of tundra plants, both on land and in water. In winter, they graze primarily on oilseed rape, sugar beet, potato, and various grasses; damage to crops can be extensive, though their grazing can also benefit particularly sugar beet and potato farmers by gleaning leaves and roots left behind after the crop is harvested, reducing the transmission of crop diseases from one year to the next.