The North American name for an aquatic bird (family Gaviidae) known in Britain and Ireland as a diver. It resembles a large duck or cormorant, with mainly brown or black and white plumage in summer, grey and white in winter. They have webbed feet set far back on the body, meaning that they swim and fly well but have difficulty walking on land. They feed on fish and other small vertebrate and invertebrate animals. There is one genus Gavia with five species found throughout northern parts of the northern hemisphere.