St. Mary Lake

Saint Mary Lake is the second-largest lake in Glacier National Park, in the U.S. state of Montana.Located on the east side of the park, Going-to-the-Sun Road parallels the lake along its north shore. At an elevation of 4,484 feet, Saint Mary Lake's waters are colder and lie almost 1,500 feet higher in elevation than Lake McDonald, the largest lake in the park, which is located on the west side of the Continental Divide. Here, the great plains end and the Rocky Mountains begin in an abrupt 5,000-foot elevation change, with Little Chief Mountain posing a formidable southern flank above the west end of the lake.

The lake is 9.9 miles long and 300 feet deep with a surface area of 3,923 acres. The waters of the lake rarely rise above 50 °F and are home to various species of trout. During the winter, the lake is often frozen over with ice up to 4 feet thick.

Source: Wikipedia