My birthday party, I neeeed ideas please?!!?!?!!?!?! :]]?

Okay so I'm having a birthday party in about a month, it's my fourteenth so I guess it's pretty special. I'm gonna have a pool party basically all day and I don't wanna bore my guests with just swimming for nine or so hours. So I need some good ideas to go along with that besides the eating, swimming, cake in the face, stuff like that :] It's gonna be about twenty people not including family that may come. Boys & girls. Soooo if anyone has any ideas, post please :]