First inlet near Portrane Martello Tower car park. 

Park the car in the car park near the Portrane Martello Tower. Head towards the sea keeping the cliff walk footpath to your right. When the tide is out, you can get down onto this secluded little beach by climbing down the rocks. There are plenty of grooves and ledges, so it is an easy climb.
It is very rewarding in terms of little caves, rock formations and secluded inlets.
Keep walking at the sea's edge across as many rock formations and caves as possible to experience the cliff walk from down below.

NOTE: Coastal walking is like playing poker. Always give yourself an out. The safest time to go is about 2 hours before low tide. At that time the tide is far enough out so that the rocks are exposed, but it also gives plenty of time before the tide starts to turn again. Check the times here: http://www.tide-forecast.com/locations/Malahide/forecasts/latest/six_day