They have webbed feet that help them swim. Their huge, parrot-like bill stores fish as they hunt underwater. It is wide in profile and narrow when viewed from the front. In breeding season, the bill becomes brightly colored. They eat mostly small fish.
Puffins dig a deep burrow in which the female lays a single egg.
Both parents feed the chick for about 6 weeks. The parents then abandon the chick who will leave the burrow after about a week without food. It will then go the sea and fish for itself. Puffins often mate for life.