The Atlantic seaboard watershed is a watershed of North America along both the Atlantic Canada (Maritimes) coast south of the Gulf of Saint Lawrence Watershed &the East Coast of the United States north of the watershed of the Okeechobee Waterway.The relatively narrow continental area is demarcated on the south by drainage to the Okeechobee Waterway (which drains both westward to the Gulf and eastward to ocean), the Eastern Continental Divide (ECD) to the west, and the Saint Lawrence divide to the north.