Porto in northern Portugal is accessible from Ireland via a number of European Gateway cities such as Heathrow, Paris, Amsterdam and Manchester. Easiest routing is probably the Cityjet service which begins on April 30 from Dublin to Lisbon and onwards with Portugalia.
Three flights a week on Monday, Wednesday and Friday at 10 a.m. get you into Porto at 3 p.m. local time. Prices are yet to be confirmed, but Dublin-Lisbon is £239.
Cheapest way to Porto if you can get the seats is with Air France via Paris at £224. British Airways via Heathrow is £272