The Gulf of Saint Lawrence is the outlet of the North American Great Lakes via the Saint Lawrence River into the Atlantic Ocean. The gulf is a semi-enclosed sea, covering an area of about 236,000 square kilometres (87,000 sq mi) and containing about 35,000 cubic kilometres (8,300 cu mi) of water, which results in an average depth of 152 metres (499 ft). It is the world's largest estuary.
The Gulf of Saint Lawrence is bounded on the north by the Labrador Peninsula and Quebec, to the east by Saint-Pierre and Newfoundland, to the south by the Nova Scotia peninsula and Cape Breton Island, and to the west by the Gaspe Peninsula, New Brunswick, and Quebec.
As for significant islands the Gulf of Saint Lawrence contains Anticosti Island, Prince Edward Island, Îles-de-la-Madeleine, Cape Breton Island, Saint Pierre Island, and Miquelon-Langlade.
Half of the ten provinces of Canada adjoin the Gulf: New Brunswick, Nova Scotia, Prince Edward Island, Newfoundland and Labrador, and Quebec.
Besides the Saint Lawrence River itself, significant streams emptying into the Gulf of Saint Lawrence include the Miramichi River, Natashquan River, Romaine River, Restigouche River, Margaree River, and Humber River.
Branches of the Gulf include the Chaleur Bay, Fortune Bay, Miramichi Bay, St. George's Bay, Bay St. George, Bay of Islands, and Northumberland Strait.
According to en.wikipedia