We are going to be taking a 12 day cruise through the British Isles. One of our stops is in Dun Laohaire. How long does it take to get from the port to Dublin? What are the must see in a one day trip? We would like to see the Guinness storehouse. I would also like to purchase a Celtic knot ring and Aron knitted sweater. Any words of advice?
It’s about a 30-minute taxi ride from the port to central Dublin. Must-sees are particluar to your interests. A good tour of Dublin can be seen by walking around the city from The General Post Office across the O’Connell Bridge to Trinity College, down Grafton Street ( pedestrianized shopping street) around the National Museum of Ireland, the Parliament Building. (Leinster House) and then St. Stephen’s Green. Then past Dublin Castle on the way back toward the O’Connell Bridge.
The thing to remember about Dun Laoghaire is that it is a tender port, so your plans for time ashore have to be flexible. As at any tender port if the sea is too rough the call can be cancelled. Even if you do get ashore you don't know what time you will do so, as you are at the mercy of how the ship organises its tenders.
Generally they will tender ship's excursions ashore first, then independent guests- in an order determined either by a ticketing system or by grade of cabin on the ship.
Then of course a need to be back well before the "all aboard time" due to the time taken to tender.
It isn't a case of arrive at x time, and leave at y time. The actual available time will be a lot less.
If you want to be a bit adventurous, the DART -- Dublin Area Rapid Transit -- stops in Dun Laoghaire. I've taken it several times. The Dun Laoghaire Mallin station is a primary stop on the DART line, and it's conveniently located near the seafront and the town center. It should get you into central Dublin in 30 minutes or so.
If you would like to see a bit of culture, Dun Laoghaire is the home of the James Joyce Tower: https://joycetower.ie/. Joyce's novel Ulysses starts at the Martello Tower. These towers were built by the English during the Napoleonic area as a form of national defense.