Lake McDonald is the largest lake in Glacier National Park. It is located at 48°35′N 113°55′W in Flathead County in the U.S. state of Montana. Lake McDonald is approximately 10 miles long, and over a mile wide and 472 feet deep, filling a valley formed by a combination of erosion and glacial activity. Lake McDonald lies at an elevation of 3,153 feet and is on the west side of the Continental Divide. Going-to-the-Sun Road parallels the lake along its southern shoreline.