This blogpost by Carolyn Shearlock, who is a boater, is good insight into the current state of affairs in the Marathon area. This was the most hard-hit zone damage-wise.
I especially liked her suggestion that anyone visiting pick up a small bag of garbage---one bag at a time, we'll get it done----and also that she encourages people to come to the Keys, as tourism provides dollars to help rebuild.
Having travelled to the Keys pre-Irma, I can only imagine the devastation that was unleashed. Her points are all good ones.