Nendrum Monastery mill, Medieval tide mill at Nendrum Monastery on Mahee Island, Northern Ireland.

Nendrum Monastery mill is a tide mill on Mahee Island in Northern Ireland powered by water from Strangford Lough. The structure features an horizontal waterwheel and millstones that were driven directly by the rising and falling of the tides.

The site dates to 787 and ranks among the earliest tide mills known to archaeology. Its construction by monks at the monastery represents an early example of technical know-how in medieval Ireland.

The monastery used the mill to grind grain for the monastic community, showing how the site combined spiritual life with practical craftsmanship. The structure was therefore central to the daily needs of those who lived there.

The site is accessible by car and has designated parking for visitors. The restored foundations are open year-round, with guided tours available to explain how the mill worked.

The mill used a clever system where water was held in basins before being released to power the wheel, a method that was unusually efficient for its time. This approach revealed the practical skill of the medieval monks who designed it.

• GPS coordinates: 54.50000,-5.64700
• Latest update: December 12, 2025 17:43