Siderno is a town and comune in the Metropolitan City of Reggio Calabria, Calabria, southern Italy, about 3 kilometres from Locri. Siderno Marin…Siderno is a town and comune in the Metropolitan City of Reggio Calabria, Calabria, southern Italy, about 3 kilometres from Locri. Siderno Marina is the newer town located on the Ionian coast. It is a destination for both Italian and foreign tourists and has a bathing beach.