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

• Latitude: 49° 34' 58'' North   (decimal: 49.5827778)
• Longitude: 70° 9' 54'' West   (decimal: -70.165)
• Topography Feature Category: Lake
• Geographical Feature: Lac
• Canadian Province/Territory: Quebec
• Location: Mont-Valin; Le Fjord-du-Saguenay
• Atlas of Canada Locator Map: Lac Os
• GPS Coordinate Locator Map: Lac Os Lat/Long