ferry rides

Five days is about right for a first taste of Northern Irleand. I'd spend it all in Belfast since I've become fascinated by the place, but an excursion to Derry and the causeway could easily be fitted in. Five days could also give you a heck of a tour in Wales - - especially if you want to see the best castles in the world (I'd only rank a couple in Spain and one in Syria as being equal). The people in both countries are drop-dead great. Wales might give you a bit more variety in geography and wins hands-down for prehistoric sites. I'm unaware of a ferry from England to Belfast, I suspect you'll have to go to Stranraer, Scotland, which will be a bit hard to get to. Along the same lines, the Dublin/Wales ferry dumps you at Holyhead, which is also in the far beyond. Each ferry ride is a couple of hours, which coupled with the time to get to the arrival/departure port, would eat up the better part of a day. You don't have time to do both countries. Wales would be my choice since you can drive the whole thing from northern England. If you pick the RoI or Northern Ireland, you might want to explore a cheap flight.

Stena Line operates ferries from Birkenhead (the city on the west bank of the Mersey opposite Liverpool) to Belfast: http://www.norfolkline.com/EN/Irish_Sea_Ferries/Belfast_Liverpool/ But the Irish Sea can be pretty rough at any time of year if you're unlucky.

To get from Ireland to Wales we used the Rosslare Harbour ferry in Rosslare, Ireland (south of Dublin). To get back over to Northern Ireland we used the ferry at Stranraer, Scotland over to Belfast. We traveled to Rosslare from Dublin and to Stranraer from York and found both drives pretty easy, though a bit lengthy. If I recall correctly, I think the ferry rides were around 2 hours.