I'm at summer camp and the best thing to do is go swimming. 
That sounds like fun, I love swimming personally, great exercise and it feels great.
Me and the other campers lay games to keep pool time fun. 
Are one of those games Marco Polo?
Sometimes. We play that game when we get tired of swimming so fast in the other games. 
Yes, swimming is very tiring. Many athletes use swimming as a form of exercise because it uses more energy underwater.
The campers and counselors often race in the different kinds of swim. My favorite is the freestyle. 
That sounds fun, I have not done it before. Camps always have fun activities!
I have to come to camp because of Summer School, but we try to make it fun anyways. I meet new people.