I spotted the reflection at first and knew i wanted to have it in the shot.
I looked at the tunnel form both sides and decided i liked how the light came into the tunnel this way.
The canal supplied the perfect line to take you through the picture. Starting from the darkness i wanted the capture how the light gets progressivly brighter. To help the contrast i exposed for the reflection. This made the end of the tunnel i am the darkest and slightly over exposed outside the tunnel. Thanks pretty much how the idea comes about. Next step is finding where to hide the watermark. This is an easy one.