Lac Mary-Grimes is a Lake located in Lac-Nilgaut; Pontiac, Quebec.

• Latitude: 46° 2' 00'' North   (decimal: 46.0333333)
• Longitude: 76° 34' 22'' West   (decimal: -76.5727778)
• Topography Feature Category: Lake
• Geographical Feature: Lac
• Canadian Province/Territory: Quebec
• Location: Lac-Nilgaut; Pontiac
• Atlas of Canada Locator Map: Lac Mary-Grimes
• GPS Coordinate Locator Map: Lac Mary-Grimes Lat/Long