Shell Island, near Harlech,  was only a true island for a short period in the 19th century. However, current access is limited due to the tides, so there is a local post for the campers there, with carriage to the nearest village by amphibious vehicle.

Recent issue have featured a seashell (obviously) and the Bee Orchids that grow there; these latter stamps being made available as se-tenant pairs in English and Welsh . The service was launched in 1999 with covers ‘posted’ 4 miles out to sea on the ridge of mud and stone called Sarn Padrig, which may or may not be a relict of the the legendary land of Cantre’r Gwaelod.

An earlier postal service may have existed perhaps in the 19th century, perhaps more recently. For a stamp inscribed Mochras, the Welsh name for Shell Island, and showing a map of the island also exists. Any information on this would be welcomed.