[The safety of not having to strain her own body into floating, being able to hold on to something that will stay floating no matter how high the tide rises,helps Gwen's brain to return to the sharpness it had lost. Looking at Karev,watching him trying to get contact something sparks in her and she reaches over the piece of debris and grasps his hand. Holding on to it hard, trying to tell him, without distracting him from what he's doing, that she's got him too.
They can't die down here. This isn't even them, of course they can't die. BUt it feels enough like them for her to be frightened. Even if dying no longer means death, Gwen has no desire to go through it.]