A group of three Second World War sea-mines are buried on the eastern mid/upper side of Caerfai beach, and occasionally become exposed when sand levels drop. They were originally washed ashore in the 1950s, were defused, and left on the beach to become buried in the sand. All three mines were re-exposed in the 1980s and again in 2013 when they were spotted and reported by a local resident. A subsequent investigation by Dyfed Archaeological Trust identified the mines as being a Type 17 deep-water moored mine. Two of the three mines were re-exposed in July 2021 and recorded via photogrammetric survey, all three mines were re-exposed again in early January 2022, and recorded via photogrammetric survey by the RCAHMW.

Dimensions:

Seamine 1 (central). Maximum exposed remains (July 2021) = 720mm x 670mm, c. 100mm proud of sand. Max diameter of rim = 615mm. Internal diameter of rim = 538mm. Rim width (max) = 44mm.

Seamine 2 (southern). Maximum exposed remains (July 2021) = 888mm x 616mm, c. 100mm proud of sand. Horn/Spike bosses = 78-82mm across, two visible examples are spaced 700mm apart, diagonally. Large corroded hole (367mm x 297mm) in one half of the mine body.

Seamine 3 (northern). Maximum exposed remains (January 2022) = 780mm x 760mm, c. 120mm proud of seabed. Max diameter of rim = 420mm. Internal diameter of rim = 340mm. Rim width (max) = 42mm.

Seamine 3, 3D Model: https://skfb.ly/ovEFQ

Sources:

https://www.bbc.co.uk/news/uk-wales-south-west-wales-21307108

https://dyfedarchaeology.org.uk/arfordir/reports/arfordirreport2012-13.pdf (pp.14-16).

J.Whitewright, RCAHMW, June 2022