Howth is a small town northeast of Dublin. It is located on a peninsula closing Dublin's bay.
You can reach Howth using the DART, a fast train service, from Dublin's city center. Return ticket costs €4.70 from Connolly, Tara or Pearse stations in the City Centre and is valid one day. There are trains every 15 minutes. Take the train north to Howth. You will arrive near the Harbour. The train takes between 25 and 30 minutes from Connolly Station.
Notice: There is one train going to Howth, and the other going to Malahide. They both go in the same direction, but do not halt at the same stations. If it's not written "Howth", it's not going there.
Alternatively, you can take a bus from Connolly, line 31 will take you up to Howth's Harbour and line 31B up to Howth's Summit. Tickets can be bought in the bus (prepare your change). There is approximately one bus every half-hour or so.
The bus needs to travel through heavy traffic and across a tram line to get to the stop opposite Connolly station and so the time can vary when it arrives, it is best to be at the Connolly bus stop at the time the bus is due to leave and be vigilant as many busses crowd the stop and some may not stop -- be assertive when hailing the bus.
The 31 and 31B both start from the same location; Eden Quay. It is just off O'Connell Street. With your back to the O'Connell Statue and facing O'Connell Bridge turn left and follow the river, you should be on the side of the road away from the river. Continue past the T-junction, where you should see the Abbey theatre. The bus stop is the second before the railway bridge.
Taxis to- and from the airport are approx. €25.
Traffic can be heavy on the causeway between Howth and the mainland. It's worth checking with you cab driver how long the journey may take, as special events such as grave blessing may impact journey times.
Think walking shoes, as you'll mostly be walking. There is only one main (and circular) road on the peninsula, that bus lines 31 and 31B take.
The old town and the harbor are very traditional. There are interesting ruins higher in the hills, and an old tomb west of the harbor.
The volunteer-run National Transport Museum is located on Howth, in the grounds of Howth Demense, although its opening hours are limited, particularly off-season when it is mainly open at weekends. Approximately 100 items of Irish transport and vehicular history are on display, including some examples of the trams which formerly ran on the Hill of Howth.
The Howth Quarry on the top of Howth Head. It is possible to drive up to the very top of the Ben of Howth (a radio mast). There are great views of Dublin bay from here and the whole area is popular with walkers. Watch for procreating couples in cars though!
At the end of the West Pier, you can see the footprints of king George IV, from when he landed there on a visit to Ireland in August 1821.
There is a walking trail starting east of the town that follows the cliffs all over to the southern part of the peninsula. Take the leftmost road from the harbour. The cliff's trail is indicated to the left a bit further. The view is breathtaking and it's really worth the walk. Along the way, you'll come across Dublin's most visible lighthouse, the Bailey Lighthouse (open for tours once a year during the summertime Howth Peninsula Festival). The southern part gives a great view of Dublin's bay and the city itself. The whole tour takes between 3 and 4 hours.
If you took bus 31B to Howth's Summit, reach the lighthouse from there (15 minutes walk), and do half the track -- towards the north or the south. When you get off the bus, you will see The Summit Inn and a steep upward road beside it. Follow that road to the summit carpark at the top and from there you can choose North(left) or South(right). North will be busier but if you go South, you will be disorientated when you reach the end as it comes out about 10 minutes walk from a bus-stop. So north may work better.
It is also possible to go towards the center of the peninsula and walk to the three hills that dominate Dublin's view over the ocean. There is a golf course between two of the hills. The view is also very nice.
It is possible to go on a birdwatching cruise to Ireland's Eye, a small island north of Howth.