Explore the amazing and scenic Cliffs of Moher. This adventure is not located far from Dublin and is best and most easily accessed via a tour from Dublin.
The best way to do this, or the easiest, would be by booking a tour. There is no bus that goes out to here, so you would have to rent a car otherwise. If you are staying in Dublin, you can book a tour at the Paddy Wagon Travel Agency for about 35 Euros. It's just on the main road by the giant metal pole.
The bus ride is about 3 hours and they take you to a small fishing town, some smaller cliffs, a place to buy an expensive lunch, and then the Cliffs of Moher. This is an amazing place to see if you are in Southern Ireland and is a great spot to shoot some photos. Like most places in Ireland, this spot can get extremely windy and rainy so wear some warm clothes!