Llanddwyn Island old lighthouse with Snowdonia in background.

Ynys Llanddwyn or Llanddwyn Island is a small tidal island off the west coast of Anglesey, north Wales. The nearest town is Newborough.

The island is very interesting geologically with pillow lava, jasper formations and aeolian sand deposits. The island also forms part of the National Nature Reserve of Newborough Warren which includes the extensive and floristically rich sand dune system. Llanddwyn Island is not always an island; it remains attached to the mainland at all but the highest tides. It provides excellent views of Snowdonia and the Lleyn Peninsula.

The island is very rich in legends and in particular the association with Dwynwen. The name Llanddwyn means "The church of St. Dwynwen". Dwynwen is the Welsh patron saint of lovers, making her the Welsh equivalent of St. Valentine. Her Saint's day is January 25 and is often celebrated by the Welsh with cards and flowers.

There are more than 10 miles of footpaths crossing Llanddwyn Island and Newborough Warren, including the Anglesey Coastal Path, and it is a very popular place to visit. The island provides a worth-while goal after the mile-long walk along the beach from the nearest car park. Llanddwyn Island, with the neighbouring beach, has been awarded Blue Flag beach status in recognition of the cleanliness of the sea and the beaches.

Llanddwyn Island in Film
In 2004, Llanddwyn Island was used as a filming location in Demi Moore's romantic thriller Half Light. Tŵr Mawr was used as a lighthouse which plays a key role in the film. CGI was used to create the effect of a real light on top of the lighthouse.

St Dwynwen's church Llanddwyn

Demi Moore 'Half Light' : Llanddwyn Island, Wales