The Bloody Stream, Howth
You should go there, just for the name alone!! :-)
They have tables outside where you can eat & drink during the summer.
They also serve food, specialising in fish dishes (of course). Their resident chef has appeared on Irish TV.
Even though it is located under the Dart station, you barely notice the sound of the trains at all.
You'll see The Bloody Stream featured under the VT Restaurant tips, but it is actually a pub that serves food, not an actual restaurant - just so that there is no confusion :)
Dress Code: Casual
As a Dubliner, this is my favourite place to go on a summers day and sit outside and have a few gargles, then go over to Mauds and get an Icecream....been doing this since a child (just without the beer of course). If your a tourist in the city, just get the dart, will only take 20 mins.
Dress Code: Smart casual, just jeans etc, as with most pubs at nighttime, shoes essential.