Three of the four leave from the same DART line, which is why Dublin works so well without a car. Glendalough needs a dedicated bus, and Newgrange is easiest on an organised tour, since public transport there is awkward. Times are one way from the centre.
A Victorian harbour town on the south side of the bay, with a long pier to stroll and the sea on both sides. The best short trip from the city.
Tip: The walk out along the pier and back along the seafront takes about 1 h. The pier is open to the wind, so bring a layer, and check the forecast first, because a gale makes it unpleasant to be out there.
Weather: Dún Laoghaire
A coastal town with a castle and gardens, about ten minutes on foot from the village.
Tip: The castle and gardens open daily from 9.30 am to 5.30 pm. Allow at least two hours. Buses 32 and 42 also run from the centre.
Weather: Malahide
A seaside town at the southern end of the DART, below Bray Head.
Tip: The cliff path to Greystones had landslides and was closed at last report. Ask at the station or check online before you plan the walk, and keep the beach as a fallback.
Weather: Bray
A glacial valley with two lakes and a monastic site in the Wicklow Mountains. The scenery is the best of the four.
Tip: Departures are limited, so check the timetable first and plan your return around the last bus. Allow the best part of a day, and book in advance in summer.
Weather: Laragh