The Pacific Black Duck is mostly mid-brown in colour, with each feather edged buff. The head pattern is characteristic, with a dark brown line through the eye, bordered with cream above and below and a dark brown crown. The upper wing colour is the same as the back, with a bright glossy green patch in the secondary flight feathers. The white underwing is conspicuous in flight. Young Pacific Black Ducks are similar to the adults in plumage.