"Robot" lifebuoy
A few days ago there was a news article (in Dutch) on a lifesaving device to be used from a beach. They refer to it as a robot, but from the article it appears to be more like a remote controlled floatation device with some kind of propulsion system, able to reach 35km/h.
One might hope it has some proximity sensors too, and not rely solely on the operator being able to avoid ramming Emily squarely into the already distressed swimmer.