Closely related to the Tufted Puffin, the Rhinoceros Auklet is a large alcid with a wedge-shaped head. It is drab-gray overall, darker above than below. In breeding plumage, the Rhinoceros Auklet has a bright orange-yellow bill adorned with a whitish horn. It also has two light feather tufts on each side of its head, going in a line back from the eye and the corner of the mouth. The juvenile appears similar to the non-breeding adult, lacking both the feather tufts and beak horn, although the lower mandible is yellow on the adult and dark on the juvenile.