Troisième lac Mercier is a Lake located in Mont-Albert; La Haute-Gaspésie, Quebec.

• Latitude: 49° 4' 30'' North   (decimal: 49.0750449)
• Longitude: 65° 54' 42'' West   (decimal: -65.9116073)
• Topography Feature Category: Lake
• Geographical Feature: Lac
• Canadian Province/Territory: Quebec
• Location: Mont-Albert; La Haute-Gaspésie
• GPS Coordinate Locator Map: Troisième lac Mercier Lat/Long