Dun Laoghaire seafront (if tendered there)
At the anchorage; DART to Dublin 20 min
If your call uses the southern anchorage, the harbour town itself earns an hour: two great Victorian piers to stroll, Teddy's famous 99 ice cream, the James Joyce tower at Sandycove (free) up the coast. The DART into Dublin hugs the bay and is half the fun.
Free