Marathon Island is a Island located in Thunder Bay, Ontario and has an elevation of 325 meters.

• Latitude: 48° 42' 55'' North   (decimal: 48.7152777)
• Longitude: 85° 38' 3'' West   (decimal: -85.6341666)
• Topography Feature Category: Island
• Geographical Feature: Island
• Canadian Province/Territory: Ontario
• Elevation: 325 meters
• Location: Thunder Bay
• Atlas of Canada Locator Map: Marathon Island
• GPS Coordinate Locator Map: Marathon Island Lat/Long