Is a medium-sized sea duck. Adult males have a dark head with a greenish gloss and a circular white patch below the eye, a dark back and a white neck and belly. Adult females have a brown head and a mostly grey body. Their legs and feet are orange-yellow. These diving birds forage underwater.
They are found in the lakes and rivers of boreal forests across Canada and the northern United States, Scandinavia and northern Russia. They are migratory and most winter in protected coastal waters or open inland waters at more temperate latitudes. Here they are wintering in Het Zwin (vogelreservaat)