A medium to large water bird; 30-38 cm TL; 192-493 g; sexes are alike in appearance. Head and neck: Frontal shield and base of bill red; tip of bill greenish yellow; head and neck dark grey to black.
Body: Overall dark grey to greyish brown; prominent wing edge and outer primaries white, creating a white line on the side of body, below wing.
Limbs and tail: Legs and feet bright yellowish green to yellow; toes long; tail grey with white feathers on the outer tail feathers when viewed from the side.