Mergellina (Neapolitan: Margellina) is a coastal district of the city of Naples, Italy. It is located in the quartiere of Chiaia. It stands at the foot of the Posillipo Hill and faces the Castel dell'Ovo. Some people say the name derives from mergoglino, a local name for the smew,[citation needed] others believe it is a corruption of Mare Giallo ("Yellow Sea"), which would refers to when the sea turned yellow due to floating tufa rock dust following an eruption of the Vesuvius.[citation needed] However, very likely the real origin of the name is from Latin mare ialinum, which stands for "clear, transparent sea".[1]