A good hat for the sun, plus a back-up if hat #1 goes for a swim. Comfy shoes for camp. A comfy & sturdy camp chair....don't skimp and bring a cheapo chair that blows out on day #2. A good headlamp & extra batteries. A good camera to capture the memories. I always bring a hammock for napping in camp if there are suitable trees. I also bring my Nook with a couple books on it, in a Pelican case. Lots of extra heavy duty moisturizer to prevent chapped & split hands/fingers/feet. A solar shower. We always bring a few decks of cards or other camp games.
Have a fun trip.