Llanddwyn is not quite an island. It remains attached to the mainland at all but the highest tides. It provides excellent views of Snowdonia and the Lleyn Peninsula and is part of the Newborough Warren National Nature Reserve. Llanddwyn Island is situated near the southern entrance to the Menai Strait. A beacon, called Tŵr Bach, was built at the tip of the island to provide guidance to ships heading for the Strait. Another more effective lighthouse, Tŵr Mawr, which was modelled on the windmills of Anglesey, was built nearby in 1845.