The Chesapeake Bay Retriever was an American bred retriever, specifically designed to withstand long days of hunting in the frigid waters of the Chesapeake Bay. Wealthy owners of duck clubs that lined the shores of the Chesapeake Bay during the 19th century focused their breeding programs on producing their ideal ducking dog. Newfoundlands, Irish Water Spaniels, and hounds of undetermined origin were among the dogs thought to be in the genetic mix. By 1884, AKC recognized the Chessie type.

To understand the Chesapeake Bay Retriever, one should consider the conditions to which these dogs were built to work.  The Chesapeake Bay is a shallow, 200-mile-long estuary situated between Maryland and Virginia. It’s water temperatures get down around freezing in early winter and stay there until spring.  Located along the Atlantic Flyway, a flight path taken by ducks and geese to their winter homes, the bay hosts a third of all migratory waterfowl wintering on the East Coast bird each year.

Old-time sportsmen hoping to exploit this duck hunter's paradise built a retriever well suited to withstand the bay's frigid waters and fierce winds. The thick, oily double coat of the Chessie is both insulating and waterproof; it repels moisture much the way a duck's feathers do. His broad chest acts a plow against the ice flows, and their powerful hindquarters and large webbed feet enable them to swim tirelessly against the slashing winds that whip across the bay. Ideally equipped to perform their primary function, this rugged breed retrieved hundreds of ducks per day, then as the story goes, guarded the catch by night as the hunters retreated to the local pubs.  True or not,  it conveys an essential truth: The Chessie is a reliable, indefatigable retriever.                                                                 source: https://www.akc.org/dog-breeds/Chesapeake-bay-retriever/