A Teen Party

In early January, I am having like this pool party which will also be a sleepover outside in my backyard. I dont really have much at my house except your basic things for a party; music, movies, pool etc. I am going to be entertaining these people for nearly 24 hours, I dont want the fun to run out and people to get bored, does anyone have any fun ideas of things we could do??? We are all aged between 15 & 17 years old, i am absolutely stumped for ideas. You got any?? i wanna make this the most memorable party i can.