Lac Martha is a Lake located in Mont-Valin; Le Fjord-du-Saguenay, Quebec.

• Latitude: 49° 10' 14'' North   (decimal: 49.1705556)
• Longitude: 70° 43' 16'' West   (decimal: -70.7211111)
• Topography Feature Category: Lake
• Geographical Feature: Lac
• Canadian Province/Territory: Quebec
• Location: Mont-Valin; Le Fjord-du-Saguenay
• Atlas of Canada Locator Map: Lac Martha
• GPS Coordinate Locator Map: Lac Martha Lat/Long