13th Birthday

I need help!!!!!
My birthday is in less than a month, i have no idea what to do.
The only thing that i could do is like a pool party or something.
But the only thing with the pool party is that i wont have a theme. Also that will only keep us busy for a certain amount of time because i KNOW that i am having a sleep over and the party is going to start at 4:00 p.m. And i need something to keep us occupied besides the pool. HELP me please i am begging you!!!
~Maya~