St. Lawrence, Gulf of

a semienclosed sea of the Atlantic Ocean, off the east coast of Canada. Newfoundland and Cape Breton Island bound it on the east; the Strait of Canso in the south, Cabot Strait in the southeast, and the Strait of Belle Isle in the northeast connect it with the Atlantic. Area, approximately 263,000 sq km. The St. Lawrence River empties into the gulf. Depths range to 572 m. Anticosti Island is in the northwestern part of the gulf, and Prince Edward Island is in the south.

The Gulf of St. Lawrence has a monsoonal climate, with cold northwesterly winds in winter and warm southwesterly winds in summer. The average air temperature in February is - 10°C, and in August 15°C. The currents form a cyclonic circulation. The average water temperature in winter is below - 1 °C, and in summer as high as 15°C. In the northeast the salinity reaches 32 parts per thousand (‰), and in the west 12–15‰. At a depth of 100 m the temperature is below 0°C, and the salinity is 32–33‰; at the bottom the temperature is 5°C, and the salinity is approximately 35‰. Tides are semidiurnal and reach 2 m. From December through May the Gulf of St. Lawrence is icebound; icebergs are not uncommon.

The Gulf of St. Lawrence is navigable. It is a fishery for, among others, haddock, rosefish, halibut, flounder, and herring. The ports are Quebec (at the mouth of the St. Lawrence River) and Sept-Îles.