I'm from Dublin, Take the Dart to Greystones direction to see the coast or opposite way to Howth or Malahide. All lovely seaside villages with great restaurants etc. Or stop off in the City , Pearse station is best for Trinity college and centre of Dublin
I actully was in Dun Laoghaire yesterday and the Dart had a 90 minute special for 2 euro.
The DART is safe for anyone wondering - just be vigilant as you would anywhere else