Hi--I was in Ft. Walton Beach August 14-18, after a cool front had come through. The water was very calm and clear for the first three days, but on the fourth day, the surf picked up, and seaweed/algae/sea grass was moving in. It was pretty ugly, but if you don't mind it, you can still swim in it. I think we were lucky because I'd heard that there was seaweed only a week or two before we got there. It seems that calm water=no seaweed and rough surf=yuck!