Holyhead, Wales, United Kingdom

Trearddur Bay

Trearddur Bay on the western coast of Holy Island, Anglesey, is one of the most popular shore-dive sites in North Wales. A series of sandy coves with rocky headlands offer protected entries onto a mixed seabed of rock, sand, kelp and small reefs in 4 to 12 metres of water. The bay is well sheltered from prevailing south westerlies and is widely used for entry-level training, refresher dives and AOWD progression by Welsh and northern English clubs. Marine life is varied for a shallow shore site: kelp forests of Laminaria hyperborea cover the shallows, with snakelocks anemones, plumose anemones, dead man's fingers, sponges, hydroids and pink coralline algae on the rocks. Resident species include ballan wrasse, corkwing wrasse, pollack, sand gobies, tompot blennies, edible crabs, spider crabs, lobsters and the occasional cuttlefish or small-spotted catshark. Visibility ranges from 3 to 8 metres and water temperatures sit between 9 and 17 degrees Celsius. Currents are weak inside the bay but stronger off the headlands.