You can reach Howth using the DART, a fast train service, from Dublin's city center. Return ticket costs €4.70 from Connolly, Tara or Pearse stations in the City Centre and is valid one day. There are trains every 15 minutes. Take the train north to Howth. You will arrive near the Harbour. The train takes between 25 and 30 minutes from Connolly Station.