I'm trying to determine whether it would be possible to avoid renting a car while in Ireland. I'd like to fly into Shannon, spend a few days in Clifden exploring the area, see Cliffs of Moher, then go up to Donegal and stay at Castle Murray for a few days before heading home. I'd probably have to get back down to Shannon to fly out. Is this doable using only bus, train and feet (with luggage)?

Thanks for your help.

The railways aren't of much use if you're travelling around the west of Ireland: the lines link Limerick, Galway, Westport, Ballina or Sligo with Dublin.
Express buses link Shannon airport, Galway, Donegal and main centres.
Local buses go to most small towns and villages, but sometimes only once or twice a day. Services are increased in the summer holiday period (mid-June to early-September).
Most buses are run by Bus Eireann (www.buseireann.ie), except in County Donegal where several private firms run local buses. There is a journey planner on Bus Eireann's website.
Bus Eireann and other firms also do day tours in summer which can be a good way of reaching places not on regular bus routes.

I can't rent a car in Ireland (too old); I travel mostly by BusEireann
BusEireann actually offers daytrips during the Tourist season from Cork City and Galway.
In remote areas where there's no bus service or buses run infrequently, I also hitch-hike.

Talk to the people at the BusEireann Counter (end of the car rental counters) in Shannon airport. They can be very helpful.
http://www.buseireann.ie
You also might be interested in one of the Tourist Travel Passes (Open Road, Irish Explorer, Irish Rover)

You shouldn't have to go back to Shannon for your flight back to the U.S. When you book your tix, make them for a Dublin return. I don't think that's even considered an 'open jaw,' and it shouldn't cost more than a few bucks over and above what a simple one destination flight would cost.

I almost always fly back from Shannon because I have relatives in Limerick and friends in Limerick City.

A few days in Clifden without a car might be difficult. I think it might be worth considering another base with more transport links -- perhaps Galway.

Of all the places we've been, I think Ireland would definitely be the hardest without a car. Everything is very rural and far apart and small with no trains that we saw.

Thanks very much! I'll check out the bus link...and consider a more suitable "base." I appreciate your help.