The Cape Cod Canal is an artificial waterway in Massachusetts connecting Cape Cod Bay in the north to Buzzards Bay in the south, and is part of the Atlantic Intracoastal Waterway. The approximately 17.4-mile (28.0 km) long canal traverses the neck of land joining Cape Cod to the state's mainland. It mostly follows tidal rivers widened to 480 feet (150 m) and deepened to 32 feet (9.8 m) at mean low water, shaving up to 135 miles (217 km) off the journey around the Cape for its approximately 14,000 annual users.

Cape Cod Bay is a large bay of the Atlantic Ocean adjacent to the U.S. state of Massachusetts. Measuring 604 square miles (1,560 km2) below a line drawn from Brant Rock in Marshfield to Race Point in Provincetown, Massachusetts, it is enclosed by Cape Cod to the south and east, and Plymouth County, Massachusetts, to the west. To the north of Cape Cod Bay lie Massachusetts Bay and the Atlantic Ocean. Cape Cod Bay is the southernmost extremity of the Gulf of Maine. Cape Cod Bay is one of the bays adjacent to Massachusetts that give it the name Bay State. The others are Narragansett Bay, Buzzards Bay, and Massachusetts Bay.