The loons are the size of a large duck or small goose, which they somewhat resemble in shape when swimming. Their plumage is largely black-and-white, with grey on the head and neck in some species, and a white belly, and all species have a spear-shaped bill.
The North American name loon comes from the bird's haunting, yodelling cry.
Loons are excellent swimmers, using their feet to propel themselves above and under water and their wings for assistance. Because their feet are far back on the body, loons are poorly adapted to moving on land. They usually avoid going onto land, except when nesting.
All loons are decent fliers, though the larger species have some difficulty taking off and thus must swim into the wind to pick up enough velocity to get airborne. Only the red-throated Loon can take off from land. Once airborne, their considerable stamina allows them to migrate long distances southwards in winter, where they reside in coastal waters.
Loons can live as long as 30 years.