Surgery cannot replace all 98,000 to 120,000 hairs on a head. It usually is used to fill in hair loss areas, or make the appearance of having hair. Hence, when you wet the grafts or go swimming they will reveal the skin below them (the hair will look very thin).  The good news is that there are other ways to deal with advanced hair loss, such as systems, that can replace your full head of hair (that are undetectable) and allow you to resume a full, normal active life including swimming, sports, sleeping, etc.  Above all, never let hair loss take control of your life, as there are real solutions with today's technology.