Look out. A lookout. Looking out for you. Her outlook.
What you did was you kept a picture of the space, whether a pool or the segment of water beyond the beach in front of your station, in your mind. You saw the whole thing but you saw it in motion and changing how it usually changed and you looked for changes that weren't the way it usually was, a still point where there had been movement, movement where there was stillness, something slipping away or flailing, a smooth silent space where moments before the water churned. You refreshed the picture every few seconds or so but without ever really looking. It was like sometimes how you can drive home and get there before you realize you don't remember driving there at all.
Look out. Her outlook.
Like the girlfriend who didn't know the sign for drowned.