Medieval map shows ‘lost’ islands of Cardigan Bay

A map found in the Bodleian Library shows two ‘lost’ islands in Cardigan Bay, possibly indicating the legendary sunken kingdom from Welsh mythology, Cantre’r Gwaelod.

Cantre’r Gwaelod was a land said to be west of present-day Wales. Accounts on the legend of Cantre’r Gwaelod vary, but the earliest depiction appears during the 13th century in the Black Book of Carmarthen, describing the land as Maes Gwyddno. In this version, the land was lost to floods when a well-maiden named Mererid allowed the well to overflow.

The more widely known variation is from the 17th century, where Cantre’r Gwaelod is described as being a low-lying land, protected from the sea by a dyke and a series of sluice gates.


Seithenyn, one of two princes responsible for the sea defences got drunk one night, resulting in the sea overrunning the defences and flooding the kingdom.

Professor Simon Haslett, honorary professor of physical geography at Swansea University, went in search of lost islands in Cardigan Bay while he was a visiting fellow at Jesus College, Oxford. His search led him to the Bodleian Library, where he identified two previously unknown islands on the 13-14th century Gough Map, one of the oldest maps of Britain.

The map shows an island offshore between Aberystwyth and Aberdyfi, while the other is located further north near Barmouth.

In a study published in the journal Atlantic Geoscience, Professor Haslett has drawn upon previous surveys of the bay and analysed data on the advance and retreat of glaciers and silt from the last Ice Age.


He believes that the map gives some sway in corroborating contemporary accounts of a lost land mentioned in the Black Book of Carmarthen, further supported by records by the Roman cartographer Ptolemy that suggested the coastline was much further west than it is today.

Download the HeritageDaily mobile application on iOS and Android

More on this topic

Markus Milligan
Markus Milligan
Markus Milligan - Markus is a journalist and the Managing Editor at HeritageDaily. His background is in archaeology and computer science, having written over 7,000 articles across several online publications. Markus is a member of the Association of British Science Writers (ABSW).



Popular stories