Coloring of the body is contrast: dark grey top with fine white spots and white bottom with separate black spots. Paws and beak are colored bright red. Across an eye from the beak there lies the black wedge-shaped horizontal strip reaching an ear aperture. Beak is long, on the end it is slightly thicker, edges are covered by small tooth-like overgrowths for keeping of caught fishes. Wings are flipper-like and strong. In water the bird pulls by wings as by fins, on land it uses them as flippers. Paws in water are using as rudders, on land serve for movement (push the body forward). In nesting season the female heats sole egg keeping it by paws. For increasing of incubating efficiency and protection against cold between tail and hips of the female plicas of skin covered with small feathers had formed. At the incubating they are heated up by blood from the numerous vessels transpiercing skin of plicas, forming warm "tent" around egg. Sole egg is very large, pear-shaped, its volume is up to 10 litres.
These birds are monogamous, pair is formed for one season. Pairing happens in water. The male and the female during rearing of posterity keep together, the male feeds hatching female and drives off possible predators. Later both parents feed up the nestling. At the moment of hatching the nestling (covered with thin down) weights about 8 kg, further it puts on weight at first time almost by 1 kg per day (eating 5 - 6 kg of fishes per day), after 3-rd month of life - on 2 kg per day and more. It becomes fully fledged completely to 2-nd month of life. To the moment of leaving in the ocean the young bird weighs up to 400 kg. Sexual maturity comes at the age of 5 years.