I see why you want to shoot this scene. Lovely location and the lighting is gorgeous. With the short Blue Hour you are dealing with at your latitude, that makes it doubly tough when you add in the weather and the tide.
When I look at it, the first thing that strikes me is that you have two images in one here; the dead tree and the mountains and together they are conflicting with each other. I wonder if working with the left hand side of the image and having a less interesting topography might not give you a stronger image?
Unlike Peter, I feel that having the tree cross the horizon strengthens this shot, as it ties the water and sky together.
I've tried to build up the left side of the image, with limited success, with Content Aware Fill, but it gives the idea of what I think might be a direction worth exploring the next time...