One Fine Day is the opera's most famous aria. It comes at the beginning of Act II, which is set three years after the action of Act I. Pinkerton, Butterfly's husband, is a US Naval Officer and he had to return to the sea shortly after their wedding. In the aria, she sings about the day he will return, seeing the ship appear on the horizon, then seeing it enter the harbour. When he arrives, they will be runited for ever. Duration: 3:00