It is a Muscovy Duck. Although generally thought to be a solid white duck, Muscovy Ducks come in various colors. They also mate with other breeds of ducks, often with Mallards, producing a multi-colored duck that is infertile.
There is a Mallard in the photograph you provided. Muscovys and Mallards are often found together.
Muscovy Duck Breed Spotlight | Backyard Poultry