Moraine Lake, Banff National Park, Canadian Rockies
According to a Wikipedia entry, "the lake gets its color from the refraction of light off the rock flour deposited in the lake on a continual basis. Rock flour, or glacial flour, consists of clay-sized particles of rock, generated by glacial erosion or by artificial grinding to a similar size. Because the material is very small, it is suspended in river water making the water appear cloudy. If the river flows into a glacial lake, the lake may appear turqoise in color as a result."
And years ago, this view was on the back of the 20 dollar Canadian bills.