Very small diving seabird, widespread in cold waters of the Southern Ocean; rarely seen from mainland. Found as singles or small groups; also 100s or even 1000s in areas with good feeding and around nesting islands. Swims low in the water and usually dives when approached or runs along the water to fly away from boats. Flight is low and fast over the sea with rapid “whirring” wingbeats; does not glide. Plumage blackish above, whitish below with no bold head pattern.