Cribinau is a small island off the south west corner of Anglesey in North Wales between Porth China and Porth Cwyfan. The nearest village is Aberffraw. The island, which can be reached on foot at low tide, is notable for the 12th century, St Cwyfan's church perched on its top. The church is known locally as the church in the sea or simply as Cwyfan. The church remains in use and is popular for weddings. Anglesey (Welsh: Ynys Môn, pronounced (IPA), roughly unniss mawn), is an island and county at the northwestern extremity of north Wales. ... Approximate extent of North Wales North Wales (known in some archaic texts as Northgalis) is the northernmost unofficial region of Wales, bordered to the south by Mid Wales. ... Aberffraw is a small village on the south west coast of Anglesey, by the west bank of the River Ffraw, at grid reference SH354693. ... The examples and perspective in this article or section may not represent a worldwide view. ...

17th century maps show the church standing on the mainland of Anglesey but erosion by the sea of the boulder clay cliffs has since separated the church onto the island. To prevent the church falling into the sea , a protective wall was built around the church. Boulder clay in geology, is a deposit of clay, often full of boulders, which is formed in and beneath glaciers and ice-sheets wherever they are found, but is in a special sense the typical deposit of the Glacial Period in northern Europe and America. ...

Cribinau and the church in the sea