Since my son is a swimmer, I've tried to get clear shots. Good for you to get the head and arm so clear in the midst of movement. the arm in the air gives an action to the shot. This person is not just gliding. And also, this person is enjoying the swim.
Hi Kostas - love the upward stroke of the arm - good feel to the image.
Face is a little dark - some shadow/Highlight adjustment might bring it up a bit.
Also played around with the cropping a bit - original might be better though - cant make up my mind.