Llanddwyn Island (Ynys Llanddwyn in Welsh) is a small peninsula/tidal island on the southcoast of the Isle of Anglesey in the welsh Snowdonia region, measuring only 0,3 square kilometers. Although small, it is quite important in many ways, both in the area of natural history, and in the area of geological heritage, but it has an important maritime past as well.

Landdwyn Island is situated near the southern entrance to the Menai Strait and became important with the increase of slate shipping from the nearby ports of Bangor and Caernarfon. The small lighthouse in my picture, called Twr Bach (Little Tower), was built at the tip of the island to provide guidance to ships heading for the Strait. No exact construction date is recorded. Later on, around 1845, a bigger lighthouse, Twr Mawr (Big Tower) was built in the island. It is nowadays out of service. The small lighthouse however, regained its function in 1975 when a new, modern navigation beacon was installed on top of it.
Llanddwyn Island is rich in geologial heritage. It has well-preserved exposures of late Neoproterozoic-Cambrian mélange, which can easlily be seen from and even on the beaches around the island. It also is very important for birds, feeding in the tidal creeks off the beaches and it provides breeding ground for countless birds in Spring.

Today, the island is uninhabited. That used to be different, given the fact that there is a row of small cottages, known as the Pilot’s Cottages, on the island. The island is furthermore associated with Saint Dwynwen. The name Llanddwyn means ‘The church of St. Dwynwen’. Dwynwen is the Welsh patron saint of lovers, the Welsh equivalent of St. Valentine. Her Saint’s day is January 25.