She wasn't trying hard enough.

She was fighting but her movements were becoming more and more sluggish. She kept looking about for half seconds as though completely unaware of the very danger that threatened to swallow her whole.

"Stop that!" Edward hissed the next time she paused again. It shouldn't have worked. Water. Even when they didn't need to breathe. Sound shouldn't have. But there was no thought. Only terror and anger. "Don't you dare give up!"