Boats can use the GNSS - Global Navigation Satellite System -To find their ways on sea and lakes
This system have some specifics function. For instance one is marking the place where a man can fall i the sea (Foule) in order to facilitate the rescue.
This system can also sail the boat him self, automatically. It's a kind of autopilot.
and finally it help boat to avois each other in case of fog or bad visibility.