I'd agree that some distant fog or a fog object or two would help add some depth to the image. I alsot think that you have the ambient light up a little high, and since there is no real world analogue to the ambient light feature, it interferes with the realism of the image. I love the water splash at the front of the boat; it looks very painterly. I'd consider a single light source to look like the image is illuminated by a flash of lightning. Very cool image, and I think you can make it something amazing.