I've got Italian sheet music of Vieni Sul Mar, and what's posted by Q above is actually a pretty faithful rendering of the first verse, but not the kind of lyrical version that I guess 2L.B.E. is looking for. And a later verse has,
"Addio, riposa, e domani/Quando l'alba a svegliarti verra/Sopra Lidi lontan, lontani,/L'infelice nocchiero sara", so the Veneto does indeed seem more likely than Naples. Maybe you should try a version yourself (borrow from J Locke, "Hear My Song..."!)