Cwm-yr-Eglwys (pronounced 'koomer-egg-lewis') is a small beach on the east side of Dinas island, on Pembrokeshire's north coast. Immediately behind the beach are a few walls and churchyard of St Brynach's church which was destroyed in the great storm of 1859. Behind this is a (pay) car park with toilets and a small caravan site. The beach is mostly sand and pebbles, and access is down a slipway. Very little beach is available at high tide and swimming is generally safe. On the eastern side of the bay is the sheltered cove of Aber Gwyn, which can be reached by walking over the rocks at low tide, or else by a 200 yard swim.
A level tarmac path leads to the neighbouring beach of Pwllgwaelod through the sheltered Cwm Dewi valley, which is rich in wildlife. The coastal path skirts Dinas Head, providing an alternative and more strenuous return route. Dogs are allowed at all times.