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Gulf of St. Lawrence

Coordinates: 48°36′N 61°24′W / 48.600°N 61.400°W / 48.600; -61.400
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Gulf of St. Lawrence
French: Golfe du Saint-Laurent
Bathymetry of the Gulf of St. Lawrence
Bathymetry of the Gulf of St. Lawrence
Coordinates48°36′N 61°24′W / 48.600°N 61.400°W / 48.600; -61.400
Basin countriesCanada
Saint Pierre and Miquelon (France)
Surface area226,000 km2 (87,000 sq mi)[1]
Average depth152 m (499 ft)[1]
Max. depth530 m (1,740 ft)[1]
Water volume34,500 km3 (8,300 cu mi)[1]

The Gulf of St. Lawrence fringes the shores of the provinces of Quebec, New Brunswick, Nova Scotia, Prince Edward Island, Newfoundland and Labrador, in Canada, plus the islands Saint-Pierre and Miquelon, possessions of France, in North America.[2][3]

The Gulf of St. Lawrence connects the Great Lakes to the Atlantic Ocean via the St. Lawrence River.[4][5][6]


Magdalen Islands, Cap-aux-Meules, Chemin du Phare, tail of storms, winds and rough seas
Gulf shore at Cape Breton Highlands National Park

At Baie-Trinité, the Pointe-des-Monts Lighthouse, a National historic site of Canada, was built in 1829-1830 on a point that ancient geographers, since Samuel de Champlain (1567-1655) himself, classified as the demarcation point between the St. Lawrence River and the Gulf of St. Lawrence.[7][8]

The Gulf of St. 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 Gaspé Peninsula, New Brunswick, and Quebec. As for significant islands the Gulf of St. Lawrence contains Anticosti Island, Prince Edward Island, Îles-de-la-Madeleine archipelago, 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, Humber River, Mingan River and others.

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 Commission of Toponymy Quebec, the St. Lawrence River becomes the gulf at Pointe des Monts on the Côte-Nord and Matane Bas-Saint-Laurent or Sainte-Anne-des-Monts La Haute-Gaspésie, the Estuary is upstream, the Gulf of St. Lawrence, much wider, downstream.[9][10]


The gulf flows into the Atlantic Ocean through the following outlets:

  • The Strait of Belle Isle between Labrador and Newfoundland: between 15 kilometres (9.3 miles) and 60 kilometres (37 miles) wide and 60 metres (200 feet) deep at its deepest.
  • The Cabot Strait between Newfoundland and Cape Breton Island: 104 km (65 mi) wide and 480 m (1,575 ft) deep at its deepest.

The Strait of Canso between Cape Breton Island and the Nova Scotia peninsula had been an outlet 1.0 km (0.6 mi) wide and 60 m (200 ft) deep at its deepest. Due to the construction of the Canso Causeway across the strait in 1955, it no longer permits exchange of water between the Gulf of Saint Lawrence and the Atlantic Ocean.


Since its appearance on maps, there has been no consensus on the demarcation of the St Lawrence River from the Gulf, nor whether it is hydrographically a gulf or an estuary.[15][16]

According to Fisheries and Oceans Canada 2023, the Estuary and Gulf of St. Lawrence planning area covers most of the Estuary and Gulf of St. Lawrence bioregion, an area with some of the warmest surface waters in Atlantic Canada during summer and the largest amount of sea ice during winter. The planning area is approximately 240,000 km².[3]

According to Encyclopedia Britannica, the name of gulf Saint Lawrence in a hydrologic context is not accurate, a gulf has to be considered more as a sea bordering the North American continent than as simply a river mouth.[17]

The International Hydrographic Organization 1953 said[18]: On the Northeast. A line running from Cape Bauld (North point of Kirpon Island, 51°40′N 55°25′W / 51.667°N 55.417°W / 51.667; -55.417) to the East extreme of Belle Isle and on to the Northeast Ledge (52°02′N 55°15′W / 52.033°N 55.250°W / 52.033; -55.250). Thence a line joining this ledge with the East extreme of Cape St. Charles (52°13'N) in Labrador.

On the Southeast. A line from Cape Canso (45°20′N 61°0′W / 45.333°N 61.000°W / 45.333; -61.000) to Red Point (45°35′N 60°45′W / 45.583°N 60.750°W / 45.583; -60.750) in Cape Breton Island, through this Island to Cape Breton [45°57′N 59°47′W / 45.950°N 59.783°W / 45.950; -59.783] and on to Pointe Blanche (46°45′N 56°11′W / 46.750°N 56.183°W / 46.750; -56.183) in the Island of St. Pierre, and thence to the southwest point of Morgan Island (46°51′N 55°49′W / 46.850°N 55.817°W / 46.850; -55.817).

On the West. The meridian of 64°30'W from Pointe-Jaune (49°04′N 64°30′W / 49.06°N 64.5°W / 49.06; -64.5) to Magpie (50°19′N 64°30′W / 50.31°N 64.5°W / 50.31; -64.5), but the whole of Anticosti Island is included in the Gulf.

Protected areas and national parks[edit]

St. Paul Island in Nova Scotia off the northeastern tip of Cape Breton Island, is known as the "Graveyard of the Gulf" because of its many shipwrecks.[19] Access to this island is controlled by the Canadian Coast Guard.[20]

In 1919 the first Migratory Bird Sanctuaries (MBS) in Canada were established under the Migratory Birds Convention Act on Bonaventure Island, on the Bird Rocks of the Magdalen Islands, and on the Percé Rock. These migratory bird sanctuaries are administered by the Canadian Wildlife Service.[21]

The Federal Government of Canada manages the National Parks of Canada along the Gulf of Saint Lawrence at Forillon National Park on the eastern tip of the Gaspé Peninsula, Prince Edward Island National Park on the northern shore of the island, Kouchibouguac National Park on the northeastern coast of New Brunswick, Cape Breton Highlands National Park on the northern tip of Cape Breton Island, Gros Morne National Park on the west coast of Newfoundland, and a National Park Reserve in the Mingan Archipelago on the Côte-Nord of Quebec.[citation needed]

The five provinces bordering the Gulf of Saint Lawrence have several provincial parks with protected coasts.[citation needed]

Undersea features[edit]

Bathymetry of the gulf, with the Laurentian Channel visible

The Laurentian Channel is a feature of the floor of the Gulf that was formed during previous ice ages, when the Continental Shelf was eroded by the Saint Lawrence River during the periods when the sea level plunged. The Laurentian Channel is about 290 m (950 ft) deep and about 1,250 km (780 mi) long from the Continental Shelf to the mouth of the Saint Lawrence River. Deep waters with temperatures between 2 and 6.5 °C (36 and 44 °F) enter the Gulf at the continental slope and are slowly advected up the channel by estuariane circulation.[22] Over the 20th century, the bottom waters of the end of the channel (i.e. in the Saint Lawrence estuary) have become hypoxic.[23]


Basque settlements and sites dating from the 16th and 17th centuries

The gulf has provided a historically important marine fishery for various First Nations that have lived on its shores for millennia and used its waters for transportation.[citation needed]

The first documented voyage by a European in its waters was by the French explorer Jacques Cartier in the year 1534. Cartier named the shores of the Saint Lawrence River "The Country of Canadas", after an indigenous word meaning "village" or "settlement", thus naming the world's second largest country.[24]

Basque whalers from Saint-Jean-de-Luz sailed into the Gulf of Saint Lawrence in 1530 and began whaling at Red Bay.[25] They established their base on the Strait of Belle Isle and worked closely with the Iroquois in the Gulf of Saint Lawrence. In 1579 the English government closed all English ports to Spanish oil imports. As a result, a third of Basque whale oil could not be sold. Basque whaling collapsed in the Gulf of Saint Lawrence and never recovered.

See also[edit]


  1. ^ a b c d "Atlantic region, Government of Canada, page 86" (PDF). publications.gc.ca. Retrieved 14 March 2018.
  2. ^ Claudine Loiselle; Jean Raveneau (December 1997). "The Environmental Atlas of the St. Lawrence" (PDF). Environnement Canada, Geography department. Université Laval. pp. 34 of 67. Retrieved 21 February 2024. A River, Estuaries, a Gulf: The Great Hydrographic Divisions of the St. Lawrence
  3. ^ a b "Estuary and Gulf of St. Lawrence". Gouvernement of Canada. Fisheries and Oceans Canada. 2023-01-27. Retrieved 19 February 2024. The area represents one of the largest and most productive estuarine/marine ecosystems in Canada and in the world.
  4. ^ Jean-Claude Therriault (2012). "The Gulf od St. Lawrence: Small Ocean or Big Estuary" (PDF). Fischeries and Oceans Canada (in French and English). Canadian special Publication of Fischeries and Aquatic Science. p. 359. Retrieved 21 February 2024. the Gulf must be considered a complete and coherent systern: for example, what happens in the Gaspé current cannot be completely isolated from the phenomena that occur elsewhere. The degree of interdependence of the various areas remains to be explored.
  5. ^ "St. Lawrence River and Seaway". Great Lakes Commission. Retrieved 22 February 2024. . . . can be divided into three broad sections: the freshwater river, which extends from Lake Ontario to just outside the city of Quebec; the St. Lawrence estuary, which extends from Quebec to Anticosti Island; and the Gulf of St. Lawrence, which leads into the Atlantic Ocean
  6. ^ "St Lawrence River". The Canadian Encyclopedia. Retrieved 22 February 2024. According to the Royal Proclamation of 1763, a line from the mouth of Rivière St-Jean on the north shore past the western tip of Île d'Anticosti to Cap des Rosiers on Gaspé marks the end of the river and the beginning of the gulf.
  7. ^ a b "The Pointe-des-Monts Lighthouse" (in French). Corporation de Promotion et de Développement du site du Phare historique de Pointe‑des‑Monts. 2024. Retrieved 25 February 2024. Built on a rocky outcrop that forms an islet at high tide, the lighthouse bears witness to a time when navigation in the Gulf of St. Lawrence was perilous.
  8. ^ Edward F. Bush (1975). "The Canadian Lighthouse" (PDF). National Historic Parks and Sites, Branch, Indian and Northern Affairs. pp. 55 of 188. Retrieved 25 February 2024. The first lighthouse, completed in 1830, had walls six feet thick at the base, tapering to two feet at the lantern deck.20
  9. ^ "Gulf of Saint Lawrence". Commission de toponymie Quebec (in French). Government of Quebec. 1968-12-05. Retrieved 23 February 2024. Sixteenth-century cartographers, historians and memorialists were most often inspired by the Spanish and Italian translations of the Brief récit, and not by the original French published in 1545 to impose the toponym Gulf of St. Lawrence
  10. ^ a b "Pointe des Monts". Commission de toponymie Quebec (in French). Government of Quebec. 1968-12-05. Retrieved 24 February 2024. These points serve as a boundary between the Estuary of the St. Lawrence River upstream and the much wider Gulf of St. Lawrence downstream
  11. ^ "Anticosti". UNESCO World Heritage Convention. 2023. Retrieved 28 February 2024. Anticosti is the best natural laboratory in the world for the study of fossils and sedimentary strata from the first mass extinction of life at the end of the Ordovician period
  12. ^ "Observatoire de la baie de Sept-Îles, phase 1" (PDF) (in French). Nordic Institute for Research on Environment and Occupational Health (INREST. 2025-04-30. p. 227. Retrieved 25 April 2024. The Port of Sept-Îles is one of the largest ports in Canada, with world-class companies on the outskirts of the Bay of Sept-Îles
  13. ^ "Les rochers aux Oiseaux". Important Bird and Biodiversity Areas in Canada. Retrieved 2 March 2024. Oil pollution is also a concern due to the proximity of the islands to the main shipping route that leads to the St. Lawrence seaway.
  14. ^ "Anse-à-la-Cabane lighthouse". Commission de toponymie Quebec (in French). Government of Quebec. 2017-05-26. Retrieved 7 March 2024. Built in 1870 and 1871, it was erected during the first wave of lighthouse construction to make navigation safe in the Gulf of St. Lawrence
  15. ^ Lionel Groulx (1960). "History of French Canada since the Discovery" (PDF) (in French). Fides, Montreal and Paris. pp. 16 of 404. Retrieved 23 February 2024. In the absence of decisive, first-hand documents, historians and cartographers can only assert probabilities.
  16. ^ Jean-Claude Therriault. "The Gulf of St. Lawrence: Small Ocean or Big Estuary" (PDF) (in English and French). Fisheries and Oceans Canada. p. 359. Retrieved 23 February 2024. The Gulf of St. Lawrence contains a wide range of hydrodynamic conditions including seasonal ice cover, polynyas, fronts, gyres, freshwater input and influences, and large seasonal variations in vertical stratification.
  17. ^ "Gulf of Saint Lawrence". Encyclopedia Britannica. Britannica, The Editors of Encyclopaedia. 2024-02-20. Retrieved 23 February 2024. body of water covering about 60,000 square miles (155,000 square km) at the mouth of the St. Lawrence River. The reefs on these surfaces, coupled with the hazards of fog and ice, have caused a large number of shipwrecks.
  18. ^ "Gulf of St. Lawrence" (PDF). Limits of Oceans and Seas. International Hydrographic organization. 1953. pp. 14 of 42. Retrieved 19 February 2024. Limits of Oceans and Seas
  19. ^ "St. Paul Island Southwest Lighthouse". Parks Canada Directory of Federal Heritage Designations. Retrieved 12 March 2023.
  20. ^ Zydler, Tom (18 October 2018). "Cruising Canada's Gulf of St. Lawrence". Cruising World. Retrieved 12 March 2023. As I stepped ashore onto a blanket-size piece of sand, I realized I was probably trespassing; landing on the island requires an official permit from the Canadian coast guard.
  21. ^ "Migratory bird sanctuaries across Canada". Government of Canada. 22 February 2011.
  22. ^ Galbraith, P.S., Pettipas, R.G., Chassé, J., Gilbert, D., Larouche, P., Pettigrew, B., Gosselin, A., Devine, L. and Lafleur, C. 2009. Physical Oceanographic Conditions in the Gulf of St. Lawrence in 2008. DFO Can. Sci. Advis. Sec. Res. Doc. 2009/014. iv + 69 p.
  23. ^ Gilbert, D., B. Sundby, C. Gobeil, A. Mucci and G.-H. Tremblay. 2005. A seventy-two-year record of diminishing deep-water oxygen in the St. Lawrence estuary: The northwest Atlantic connection. Limnol. Oceanogr., 50(5): 1654–1666.
  24. ^ "French navigator Jacques Cartier sails the St. Lawrence River". A&E Television Networks. Retrieved 14 June 2021.
  25. ^ "Red Bay National Historic Site". 9 February 2022.

External links[edit]