The Maligne River flowing through Maligne Canyon in the Canadian Rockies, Alberta. Yes, it is really that blue, which is due to "rock flour" from the glacier that feeds the river.
Shot with the 50mm prime lens at f/1.8, because not much sunlight was reaching the floor of the canyon. I did some postprocessing to lighten up the dark areas. I really like the composition and the colours on this one.