The beach at Avalanche Lake, in Glacier National Park. Captured as a 5-exposure HDR and seen here with moderate tone mapping.
The crazy color of the water is actually very faithful to what was present in the scene. Like most of Glacier's alpine lakes, this one consists of glacial runoff and the large amount of sediment in the water gives it this color. The color actually changes from green to blue to turquoise and back - all right in front of you while you watch!
For those who have never been to this area, I think mtnguyd would agree with me in saying it is truly one of the 'Last Best Places on Earth'. Go before all of the glaciers melt!