Lac Saint-Castin is a Lake located in Lac-Nilgaut; Pontiac, Quebec and has an elevation of 420 meters.

• Latitude: 46° 58' 40'' North   (decimal: 46.9777778)
• Longitude: 76° 51' 12'' West   (decimal: -76.8533333)
• Topography Feature Category: Lake
• Geographical Feature: Lac
• Canadian Province/Territory: Quebec
• Elevation: 420 meters
• Location: Lac-Nilgaut; Pontiac
• Atlas of Canada Locator Map: Lac Saint-Castin
• GPS Coordinate Locator Map: Lac Saint-Castin Lat/Long