Selected by Matt Wragg - I've seen a few experiments with in camera double exposures in recent years, and it usually doesn't do it for me. This however, is stunning. The texture of the mountains really adds a great element to an already good action shot.
This isn't photo editing. Several current top-end cameras (Nikon D4S, Canon 1DX) have an in-built function to produce double exposures - the modern equivalent of what would have been exposing the same piece of film twice to achieve this kind of effect. To do something like this in Photoshop would be relatively easy as you have time to match the two shots perfectly, to do it in-camera like this is incredibly difficult.