Capri

I would suggest that the Gulf of Naples (Golfo di Napoli in Italian) is more commonly known in English as the Bay of Naples, even though Wikipedia refers to it as the Gulf of Naples ("also called the Bay of Naples").

Also, I wouldn't agree that the island of Capri is in the Bay (or Gulf) of Naples (even though Wikipedia says it is). Geographically, it's part of the Sorrento peninsula, which contains the bay to the south-east; I would suggest that Capri forms part of that boundary.