In photography you will hear the Japanese term Bokeh which refers to the out of focus rendering in the background of a photo. With this compositional technique you are telling the eye where to focus on, which in this case is the flower, while not making the boats compete for attention. The beauty of this is you can still tell there are boats in the Karystos port, but being blurred it adds a velvet touch to the scene.
This method is primarily used with people to make the subject pop in the image. Your focus point must be very precise and you usually need to use a lens with a very wide open aperture, more often than not a prime lens. In this case, I used a 35mm equivalent 1.4 lens.