13 Yr Old Party Ideas!

Hey My friends having a birthday Party and she needs help with some ideas. She lives on a lake but since this is going to be her last B-day party with all her friends before she moves. She wants something more creative than just swimmming and tubing like every other year. Me and her arent so far apart in fact we are only 8 days and im having a mall party :D..But anyway if you have any ideas on what to do thats not very costly that would be great!! Thanks for looking