If you think she only did it for the money, you haven't even 'scratched the surface'. [=there are many other factors, reasons, etc., involved]
Despite the 'surface' differences between the two candidates, they are very similar in most ways.
The tension between them is beginning to 'rise to the surface'. [=it is becoming easy to see]
(..) He took the booth near the window so he could see everyone who drove up. He wanted to make sure I wasn't tailed. He was jumpy. He hadn't touched a thing. On the surface, everything was supposed to be fine. We were supposed to be discussing my case. But I had a feeling Jimmy was trying (..)1990 Goodfellas