Very small diving seabird. Fairly common locally in fjords, channels, and the Strait of Magellan, where it can be seen from shore and ferries; uncommon out in open ocean. 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 contrasting white neck sides and a black cap, unlike other diving-petrels.