What would go good with these short board shorts?

I am going to California soon, and I needed a swimsuit . I found these board shorts (http://www.roxy.com/product/index.jsp?productId=11273265&clickid=cart) I like since I have a gross and it would over it up more. I need a top to go with them I am not allowed to wear a bikini:( I need a takini . NO ONE PEICES(: thanks! I am 13 btw.