Served by a single infrequent bus service from Nice (TAM new Route 81, not Sundays), accessible on foot either from Pont St Jean or Beaulieau on the Nice-Monaco bus line (TAM Route 100 euro 1.30).
Be prepared for long gaps between services, and an early close to the last bus.
If you plan to go to the beach near the port and it is NOT on a Sunday or holiday, you can take the bus number 111 and get off at the "Mairie" bus stop.
IMPORTANT: Very infrequent service, so always check the bus timetable beforehand.