First we played this game called the Octopus Relay. It was sooooo much fun, and it was way easy. The instructions are on the link, but one change I made was I hot glued some google eyes, a pom pom nose, and a pipe cleaner for a mouth. The kids played that for like 10 minutes...which in toddler time is practically an eternity.
Then we did the water balloon toss with the towels....kind of like water balloon volleyball, only without a net, with out teams, and without rules of any kind. It pretty much turned into a water balloon fight.
Then we played dodgesponge. It's basically prison ball with wet sponges. I got the idea from somewhere like 4 years ago for girls camp, but I can't remember where to give them credit. Anywho, you get two buckets and fill them with big poofy car washing sponges (I ripped the sponges in half). Fill the buckets with water and add the sponges. Divide the kids into two teams...each team gets a bucket. Basically, you huck wet sponges at each other...if you are hit, you are in prison, and you can get back in the came if someone catches a sponge or if you hit someone while you're in prison. The boys ESPECIALLY loved this game.
The rest of the party was just playing on the slip n slide, the kiddie pool with the slide in it, and jumping on the wet tramp. It was wonderful.
I don't get to do summer parties very often because all of our birthdays fall between fall and spring, so this was a fun opportunity to know what summer birthday kids feel like :)