It's actually an area in county Cork, but there is a national park there with a forest walk that has amazing views from the top. Actually the source of the river Lee is there. Near the forest there is a church by a lake, usually with some swans on it. The scene is like something from a story-book. Also in the neighbouring village you might hear the locals speaking Irish Gaelic because it's a gaeltacht area.
I think its one of the most beautiful places in Cork and as Carol said it is really magical no matter what time of the year you go there at. Rain, sun or snow it gives you a warm feeling as the idea that you might just run into a leprechaun (Fairy/Elf/Goblin) around the next corner.
The site of Celtic midsummer celebrations, a Catholic hermitage and pilgrimage site, and, more recently, national park and forest preserve, Gougane Barra, with its steep hillsides, lush forests, and jewel-like alpine lake, has captured the imagination of mystics and seekers for millenia. It’s off the beaten path – you can’t easily get there by bus or train, and you won’t find it in most guidebooks, but do make the effort as its mind blowing and enchanting.