This species is the smallest eider at long. The male is unmistakable with his white head marked by a thick black eye ring and greenish-black tufts of feathers on the forehead and the back of the head. Chin, throat and neck are also black, as are the back, tail, and rump. Wings are dark bluish-purple with white edging. When folded, they give a striped appearance across the back. The speculum is metallic blue bordered with white. The breast and flanks are cinnamon-buff marked with a black spot on each side just above the waterline. Legs, feet and bill are dark bluish-grey.