I did the walk from Graball, along the cliff to Churchbay, up the hill to Templebreedy, down the hill to Fennel's bay, across to Myrtleville, Fountainstown and to the rusting boat at Fountainstown beach west. Took about 2 hours but I can feel my muscles aching today.
Cork harbour was resplendent in the sunshine and I noticed above Church Bay that there are a number of tidal inlets on the left as you're on the beach. Never swam there but I've seen local teens jumping off the rocks. If you timed it according to the tides you could be there when it's shallow at low tide, or deep at high tide, or mellow in between. A pity that Church Bay is a storm beach like Fennel's Bay. All stones and little sand. Usually quiet though.
The cliffside walk from Graball to Churchbay can be a bit dodge. Compared to 6 weeks ago it's very overgrown and you have to watch the ground for anything to trip you up. You'd be over the edge of the cliff in some places. Probably not suitable for very young people who get distracted easily!