HELP ME I'M NERVOUS!!!!?

I go to this camp were, we have these "Water wars" and I'm extremely nervous. This is going to be my third year going and I never did it. We do this event where you put on a soaking wet T-shirt and swim to the other side. Theirs not that much people there. But i'm not a good swimmer and I really don't want to be laughed at T_T... I did this other event last year were we go into a canoe and push the water with or hands to the other side. And I had fun with that :D I'm running out of excuses not to go to that event. I'm tired of running please help T_T