This has a very nice sense of drama… I wouldn't lighten it because that would take away from the overall feeling here, but I think the sky could use some work to bring out some clarity of details. While the water has beautiful details and interest in this dark setting, the clouds seem to be a bit noisy and flat. I wouldn't say you necessarily need to have them exactly as clear as the water, just enough to bring the whole image into balance. 8•)