The Massachusetts Bay, also called Mass Bay, is one of the largest bays

Headlands and bays

Headlands and bays are two related features of the coastal environment.- Geology and geography :Headlands and bays are often found on the same coastline. A bay is surrounded by land on three sides, whereas a headland is surrounded by water on three sides. Headlands are characterized by high,...

 of the Atlantic Ocean

Atlantic Ocean

The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...

 which forms the distinctive shape of the coastline of the U.S. state

U.S. state

A U.S. state is any one of the 50 federated states of the United States of America that share sovereignty with the federal government. Because of this shared sovereignty, an American is a citizen both of the federal entity and of his or her state of domicile. Four states use the official title of...

 of Massachusetts

Massachusetts

The Commonwealth of Massachusetts is a state in the New England region of the northeastern United States of America. It is bordered by Rhode Island and Connecticut to the south, New York to the west, and Vermont and New Hampshire to the north; at its east lies the Atlantic Ocean. As of the 2010...

. Its waters extend 65 miles (105 km) into the Atlantic Ocean. Massachusetts Bay includes the Boston Harbor

Boston Harbor

Boston Harbor is a natural harbor and estuary of Massachusetts Bay, and is located adjacent to the city of Boston, Massachusetts. It is home to the Port of Boston, a major shipping facility in the northeast.-History:...

, Dorchester Bay

Dorchester Bay (Boston Harbor)

Dorchester Bay is the smallest of the three small bays of southern Boston Harbor, part of Massachusetts Bay and forming the south shoreline of the South Boston neighborhood and northeast shoreline of the Dorchester neighborhood of Boston, as well as the north shore of the city of Quincy in...

, Quincy Bay

Quincy Bay

Quincy Bay is the largest of the three small bays of southern Boston Harbor, part of Massachusetts Bay and forming much of the shoreline of the city of Quincy, Massachusetts. Locally in the Wollaston neighborhood of Quincy it is known as Wollaston Bay...

 (both part of the Outer Boston Harbor), and Hingham Bay

Hingham Bay

Hingham Bay is the easternmost of the three small bays of outer Boston Harbor, part of Massachusetts Bay and forming the western shoreline of the town of Hull and the northern shoreline of Hingham in the United States state of Massachusetts. It lies east of Quincy Bay and is met at the southwest by...

. Massachusetts Bay is itself part of the Gulf of Maine

Gulf of Maine

The Gulf of Maine is a large gulf of the Atlantic Ocean on the east coast of North America.It is delineated by Cape Cod at the eastern tip of Massachusetts in the southwest and Cape Sable at the southern tip of Nova Scotia in the northeast. It includes the entire coastlines of the U.S...

, which reaches from Cape Cod up to Nova Scotia

Nova Scotia

Nova Scotia is one of Canada's three Maritime provinces and is the most populous province in Atlantic Canada. The name of the province is Latin for "New Scotland," but "Nova Scotia" is the recognized, English-language name of the province. The provincial capital is Halifax. Nova Scotia is the...

.

The bay is enclosed on the north by Cape Ann

Cape Ann

Cape Ann is a rocky cape in northeastern Massachusetts on the Atlantic Ocean. The cape is located approximately 30 miles northeast of Boston and forms the northern edge of Massachusetts Bay. Cape Ann includes the city of Gloucester, and the towns of Essex, Manchester-by-the-Sea, and...

. Just south is Cape Cod Bay

Cape Cod Bay

Cape Cod Bay is a large bay of the Atlantic Ocean adjacent to the U.S. state of Massachusetts. Measuring 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....

. Cape Cod Bay is sometimes construed as part of Massachusetts Bay; under this interpretation, the name "Massachusetts Bay" denotes the entire rectangular area of ocean between Cape Ann and Cape Cod

Cape Cod

Cape Cod, often referred to locally as simply the Cape, is a cape in the easternmost portion of the state of Massachusetts, in the Northeastern United States...

. The bay's westernmost point is situated at Boston

Boston

Boston is the capital of and largest city in Massachusetts, and is one of the oldest cities in the United States. The largest city in New England, Boston is regarded as the unofficial "Capital of New England" for its economic and cultural impact on the entire New England region. The city proper had...

.

The bay gave its name to the Massachusetts Bay Colony

Massachusetts Bay Colony

The Massachusetts Bay Colony was an English settlement on the east coast of North America in the 17th century, in New England, situated around the present-day cities of Salem and Boston. The territory administered by the colony included much of present-day central New England, including portions...

, one of the two predecessor colonies of the current state of Massachusetts. Massachusetts Bay, along with Quincy Bay, Narragansett Bay

Narragansett Bay

Narragansett Bay is a bay and estuary on the north side of Rhode Island Sound. Covering 147 mi2 , the Bay forms New England's largest estuary, which functions as an expansive natural harbor, and includes a small archipelago...

, Buzzards Bay

Buzzards Bay (bay)

Buzzards Bay is a bay of the Atlantic Ocean adjacent to the U.S. state of Massachusetts. It is approximately 28 miles long by 8 miles wide. It is a popular destination for fishing, boating, and tourism. Since 1914, Buzzards Bay has been connected to Cape Cod Bay by the Cape Cod Canal...

and Cape Cod Bay, is also one of the bays adjacent to Massachusetts that give the commonwealth the nickname "the Bay State".