The term "Sea Duck" refers to a group of diving ducks that primarily inhabit coastal waters and are known for their ability to dive underwater to forage for food. Common species include the Common Eider, Harlequin Duck, and Surf Scoter. These ducks are often found in marine environments, where they feed on mollusks, crustaceans, and other aquatic organisms. Sea ducks are characterized by their robust bodies, broad bills, and distinctive plumage, which can vary significantly between males and females. They typically breed in northern regions and migrate south during the winter months, seeking open water and abundant food sources.