Ynys Llanddwyn is a small tidal island off the west coast of Anglesey, northwest Wales. The nearest settlement is the village of Newborough.
Tŵr Bach lighthouse with Snowdonia in background
The ruins of St Dwynwen's Church, Llanddwyn
The south east view of St Dwynwen's Church depicted on a print engraving from 1742 by publishers Samuel and Nathaniel Buck.
Tŵr Mawr lighthouse and cross at Llanddwyn.
A tidal island is a raised area of land within a waterbody, which is connected to the larger mainland by a natural isthmus or man-made causeway that is exposed at low tide and submerged at high tide, causing the land to switch between being a promontory/peninsula and an island depending on tidal conditions.
St Michael's Mount, Cornwall, at high tide, c. 1900
Cramond Island, Scotland, at high tide: the causeway is submerged, but the anti-boat pylons are still visible
Mont Saint-Michel in Normandy
Rough Island opposite Rockcliffe, Dumfries & Galloway, Scotland