Castellammare di Stabia is a comune in the Metropolitan City of Naples, Campania region, in southern Italy. It is situated on the Bay of Naples about 30 km (19 mi) southeast of Naples, on the route to Sorrento.

The Metropolitan City of Naples is a metropolitan city in the Campania region of Italy. Its capital is the city of Naples. The province was established on 1 January 2015 and contains 92 comuni . It was first created by the reform of local authorities and established by Law 56/2014, thus replacing the province of Naples in 2015.