Situated on north end of Bay of Naples which is located in northern section of Gulf of Naples. Inner harbor is largely protected by a detached breakwaterDiga Forania Emmanuele Filiberto Duca d'Aosta and an attached breakwater Molo San Vincenzo.
Entire harbor is bordered on west clockwise through east by mainland Italy.
Outer harbor is protected from the open sea waves except from south clockwise through west-southwest.