Lac Mathieu is a Lake located in L'Anse-Saint-Jean; Le Fjord-du-Saguenay, Quebec.

• Latitude: 48° 0' 28'' North   (decimal: 48.0078041)
• Longitude: 70° 23' 49'' West   (decimal: -70.3970175)
• Topography Feature Category: Lake
• Geographical Feature: Lac
• Canadian Province/Territory: Quebec
• Location: L'Anse-Saint-Jean; Le Fjord-du-Saguenay
• Atlas of Canada Locator Map: Lac Mathieu
• GPS Coordinate Locator Map: Lac Mathieu Lat/Long