Gulf of St. Lawrence
French: Golfe du Saint-Laurent
Canadian Shield bedrock, on the site of Pointe-des-Monts hamlet Lighthouse[1]
Bathymetry of the Gulf of St. Lawrence
Coordinates	48°36′N 61°24′W / 48.600°N 61.400°W / 48.600; -61.400
Type	Gulf
Basin countries	Canada Saint Pierre and Miquelon (France)
Surface area	226,000 km2 (87,000 sq mi)[2]
Average depth	152 m (499 ft)[2]
Max. depth	530 m (1,740 ft)[2]
Water volume	34,500 km3 (8,300 cu mi)[2]

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.^[3][4]

The Gulf of St. Lawrence connects the Great Lakes to the Atlantic Ocean via the St. Lawrence River.^[5][6][7]

The secrets of the Saint-Laurent,^[8] marine weather guide 2013, of 100 pages, provides information on a multitude of facets of the great river in all seasons. In winter, the St. Lawrence River is an immense ice factory. The machine starts up in December with the formation of ice cubes between Montreal and Quebec City. The prevailing winds and currents push this ice towards the estuary,^[4] it reaches the east of Les Méchins at the end of December. Ice covers the entire gulf in January and February.

Ice helps navigation because it prevents the formation of waves and therefore spray, ice has the advantage of preventing the icing process of ships.^[8]

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.^[9][10]

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.

• Gulf of St. Lawrence Overview
• 
  Magdalen Islands, Cap-aux-Meules, Chemin du Phare, tail of storms, winds and rough seas
• 
  Aerial view, bay of Sept Îles, port^[11] and city of Sept-Îles
• 
  Baie au Caplan, river flat, Anticosti Island^[12]
• 
  Crevettier Manic V, 11853, at the wharf, La Haute-Gaspésie, Sainte-Anne-des-Monts
• 
  Percé Bay, Percé (City), Percé rock and its obelisk, Gaspésie-Îles-de-la-Madeleine
• 
  Cape Breton Highlands National Park, Nova Scotia
• 
  Rose Blanche-Harbour le Cou,^[13][14] Rose Blanche Bay, Newfoundland & Labrador

Besides the St. Lawrence River itself, significant streams emptying into the Gulf of St. 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.^[15][16]

• Lighthouses Overview
• 
  Bird Rocks,^[17][18] keepers'house and outbuildings, Magdalen Island
• 
  L'Anse-à-la-Cabane^[19] (Hamlet), Magdalen Island
• 
  Pointe-des-Monts,^[9] keeper's house and outbuildings
• 
  Port-Daniel-Gascons, Chaleurs Bay, Gaspésie-Les Îles-de-la-Madeleine^[20]

Large marine mammals travel in all the seas of the earth, the research and observations of these giants concern fishermen and shipping industry, exercise a fascination and a keen interest for laymen and, subjects of endless studies for scientists from Quebec, Canada and around the world.^[21][22][23]

Thirteen species of cetaceans frequent the waters of the estuary and the gulf of the St. Lawrence River.^[24]

1. Hyperoodon ampullatus. — Hypéroodon boreal, Hypéroodon arctique. — (Northern Bottlenose Whale).
2. Delphinapterus leucas. — Béluga, Bélouga, Baleine blanche, Dauphin blanc, Marsouin blanc. — (Beluga Whale).
3. Physeter macrocephalus. — Grand cachalot, Cachalot, Cachalot macrocéphale. — (Sperm whale).
4. Lagenorhynchus acutus. — Lagénorhynque à flancs blancs, Dauphin à flancs blancs. — (Atlantic white-sided dolphin).
5. Lagenorhynchus albirostris. — Dauphin à nez blanc, Dauphin à bec blanc, Lagénorhynque à bec blanc. — (White-beaked dolphin).
6. Orcinus orca. — Orque, Épaulard. — (Killer Whale).
7. Globicephala melas. — Globicéphale commun, Globicéphale noir, Dauphin pilote. — (Long-Finned Pilot Whale).
8. Phocoena Phocoena. — Marsouin commun, Cochon de mer, Dieu des mers. — (Harbour Porpoise).
9. Eubalaena glacialis. — Baleine franche de l'Atlantique nord, Baleine noire de l'Atlantique nord, Baleine de Biscaye. — (North Atlantic Right Whale).
10. Balaenoptera acutorostrata. — Petit rorqual. — (Minke whale).
11. Balaenoptera musculus. — Baleine bleue, Rorqual bleu. — (Blue whale).
12. Megaptera novaeangliae. — Rorqual à bosse, Baleine à bosse. — (Humpback whale).
13. Balaenoptera physalus. — Rorqual commun. — (Fin whale).

• Sea Trip to Observe Marine Fauna
• 
  Humpback whales, dorsals, pectoral fins, Jacques Cartier Strait,^[25] North of Anticosti Island
• 
  Whale, expedition organized by Observation littoral Percé (1995), Gaspé Bay

Around Anticosti Island and to flow into the Atlantic Ocean, the waters of the Gulf take the following straits:

• Jacques Cartier Strait, between the shore of Côte-Nord region and the North of Anticosti Island.^[26]
• Honguedo Strait, a wide passage between the Gaspésie peninsula and Anticosti Island.^[27]
• Strait of Belle Isle^[28] 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.
• Cabot Strait, about 56 miles wide, is the entrance to the Gulf of St. Lawrence between Cape Ray, Newfoundland, and Cape North, the NE point of Cape Breton Island.^[29]
• Strait of Canso^[30] is located between Cape Breton Island and mainland Nova Scotia, it originally served as an outlet 1.0 km (0.6 mi) wide and 60 m (200 ft) deep at its deepest.^[31][32] Due to the construction of the Canso Causeway across the strait in 1955, the roadway no longer allows exchange of water between the Gulf of St. Lawrence and the Atlantic Ocean.^[33]

• Around Anticosti Island & Atlantic Ocean Outlets
• 
  Jacques-Cartier Strait, North of Anticosti Island, observation of marine mammals^[34]
• 
  Honguedo Strait, Gaspé, Saint-Maurice-de-l'Échouerie village,^[35] municipal stop of the Old Factory
• 
  Strait of Belle Isle,^[28] Bvrd. Docteur-Camille-Marcoux, (Route nº 138), Blanc Sablon, Quebec
• 
  Cabot Strait,^[31] from White Point, Cape Breton Island St. Paul Island^[29] in the distance, Nova Scotia.
• 
  Strait of Canso,^[31] Canso Causeway,^[33] Nova-Scotia

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.^[36][37]

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.^[4]

According to Encyclopedia Britannica, the name of Gulf St. 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.^[38]

The International Hydrographic Organization 1953 defines it as follows:^[39]

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^[28] 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.

Western Honguedo Strait Coral Conservation Area, create following the signing of the Canada–Quebec Collaborative Agreement to Establish a Network of Marine Protected Areas in Quebec in March 2018.^[40][41]

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.^[42] Access to this island is controlled by the Canadian Coast Guard.^[43]

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.^[44]

The Federal Government of Canada manages 37 National Parks of Canada,^[45] overview of the parks touching the Gulf of St. Lawrence: Mingan Archipelago National Park Reserve, in Côte-Nord, 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.^[45][46]

In Quebec, since March 31, 2024, the network of protected areas^[47][48] extends over 274,431 km2 and is established as follows:

• Continental environment (terrestrial and fresh water): 255,377 km2 or 16.89%;
• Marine and coastal environments: 18,991 km2 or 12.21% distributed as follows:
• Marine protected areas and territories set aside in the marine environment: 16,140 km2 or 10.39%;
• Portions of territories in marine and coastal environments associated with protected areas whose conservation objectives do not specifically target the marine environment (national parks, national park reserves of Quebec and Canada, migratory bird sanctuaries, planned aquatic reserves, reserves of projected biodiversity, areas of concentration of aquatic birds, etc.): 2,854 km2 or 1.84%;
• Plan Nord territory: 229,021 km2 or 19.19%.^[49]

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

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 St. 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 St. 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.^[50] Over the 20th century, the bottom waters of the end of the channel (i.e. in the St. Lawrence estuary) have become hypoxic.^[51]

Almost all of Quebec's ports are located along the St. Lawrence River seaway, from its source to its gulf, to the Atlantic Ocean. There are dozens and dozens of shelters, harbors, natural ports, large and small along the gulf up to the source of the St. Lawrence River, we can add village or individual wharf, without forgetting the large international maritime transport ports. In its annual report on maritime traffic in Canada, the Federal Bureau of Statistics gives detailed annual statistics for the years 2019, 2020, 2021, 2022, 2023^[52][53]

Ports of the Gulf of St. Lawrence, on the Côte-Nord Shore: Blanc-Sablon, Harrington Harbor, Natashquan, Havre-Saint-Pierre, Mingan, Port-Menier (Anticosti Island), Cap-aux-Meules (Îles-de-la -Madeleine).^[52]

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.^{[54][55][56][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 St. Lawrence River "The Country of Canadas", after an indigenous word meaning "village" or "settlement", thus naming the world's second largest country.^[57]

Basque whalers from Saint-Jean-de-Luz sailed into the Gulf of St. Lawrence in 1530 and began whaling at Red Bay.^[58] They established their base on the Strait of Belle Isle^[28] and worked closely with the Iroquois in the Gulf of St. 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 St. Lawrence and never recovered.

• Anticosti Island
• Atlantic Ocean
• Estuary of St. Lawrence
• Maritime Peninsula
• St. Lawrence Seaway

Wikimedia Commons has media related to Gulf of Saint Lawrence.

• Eric W. Morse 1968, Fur Trade Canoe Routes of Canada /Then and Now, pp 121
• Frère Marie-Victorin (1885-1944), Anticosti, land with immense spaces, the sea all around, and a social world of the 1920s gone forever. Anticosti/UdeM archives, 14 photos (French)
• Species of cetacean, comparison poster, Encyclopedia Britannica 2024
• Integrated Access to Knowledge and Open Data of the St. Lawrence, St. Lawrence Global Observatory (SLGO). (French)
• Atlas of the biodiversity of northern Quebec, Ministère de l’Environnement et de la Lutte contre les changements climatiques (MELCC). (French)
• Rare plants of the Mingan Archipelago Environnement Canada, 2025 (French)
• The lighthouse Trail, Bas-Saint-Laurent, Gaspésie, Côte-Nord, Îles de la Madeleine (French)
• The New Map of Empire. How Britain Imagined America before Independence, Harvard University Press
• Mapping Land Tenure Pluralism in the St. Lawrence River Valley, Julia Lewandoski, essay kicks off a Borealia series on Cartography an Empire
• Légendes du Saint-Laurent, Récits des voyageurs, Jean-Claude Dupont, 1985, 72 pages (French)
• Radio Aids to Marine Navigation 2024, Radio Aids to Marine Navigation 2024, (Atlantic, St. Lawrence, Great Lakes, Lake Winnipeg, Arctic and Pacific) Fisheries and Oceans Canada, 298 pages
• Royal Canadian Geographial Society, Maze to the Aguanish, a 680 kilometre canoe trip through the wilds of Labrador and Quebec, that traverse the headwaters of the Romaine and the Petit-Mécatina rivers, 2021
• The Gulf of St. Lawrence - a Unique Ecosystem, Government of Canada 2005 [English | French]
• Timing and position of late Wisconsinan ice-margins on the upper slope seaward of Laurentian Channel David J. W. Piper et Adam Macdonald, 2001, 11 page