In reply to Tom Valentine:
There are rocky bits from the castle in Criccieth all the way along to porthmadog, the best bits for some low key bouldering are probably low tide on the west side of the castle, the west end of black rock sands (graig ddu, some easy slabs too) and small bits at borth y gest. Nothing of amazing quality, you are probably better just driving a little bit, Tremadog is only 10mins away.