Your real holiday will start after your defense. So start planning for it. I think still there will be something for you to do.
It's good to hear that your friend is dedicated to learning how to swim and it's needed. I think you can also try to learn to swim. It's not so difficult either. Just take the first step.
As for me, my first step would be motivating myself to even get into the the water. I have someone who promises to teach me but I'm scared.