It's my understanding the South China Sea is, compared to open ocean, really more of a shallow lake that happens to be teaming with Chinese subs. American ones,

It's my understanding the South China Sea is, compared to open ocean, really more of a shallow lake that happens to be teaming with Chinese subs. American ones, too, for that matter. If the plane did hit this body of water, would these subs have noticed it? If so, are they keeping silent as a matter of tradecraft, to avoid showing their capabilities to the other side?