Lac Saint-Pierre is a large lake located in the province of Quebec, Canada. It is part of the St. Lawrence River system and is situated between the cities of Trois-Rivières and Sorel-Tracy. The lake covers an area of approximately 90 square kilometers and is known for its rich biodiversity, including various fish species and migratory birds. The lake is also recognized for its ecological importance and is designated as a UNESCO Biosphere Reserve. It serves as a vital habitat for wildlife and supports recreational activities such as fishing, boating, and birdwatching. The surrounding region features beautiful landscapes and is popular for outdoor enthusiasts.