Adults are 55–65 cm long with an 88–106 cm wingspan, and weigh 350–550 grams. The plumage is often all white, but can also be blue-grey. In the breeding season, the adult has two long plumes on the nape that form a crest. There are similar feathers on the breast, but the barbs are more widely spread. The legs are black and the feet yellow. Juveniles are similar to non-breeding adults but have greenish-black legs and duller yellow feet. The subspecies nigripes differs in having yellow skin between the bill and eye, and blackish feet.