Hints Of "Welsh Atlantis" Sunken Kingdom Seen On Medieval Map

The kingdom of Cantre’r Gwaelod lives on the blurry line between fact and fiction


Tom Hale

Senior Journalist

clockAug 22 2022, 15:38 UTC
Sunset bathes a submerged forest exposed on the beach at low tide on Borth sands near Ynysla along Cardigan Bay, Wales.
Sunset bathes a submerged forest exposed on the beach at low tide on Borth sands near Ynysla along Cardigan Bay, Wales. Image credit: Richerman/Wikimedia Common

Welsh legend speaks of a long-lost sunken kingdom known as Cantre’r Gwaelod, once found off the rocky shores of Cardigan Bay in the Irish Sea. While hard evidence of the “Welsh Atlantis” has been lacking, a fresh analysis of one of the oldest surviving maps of Great Britain suggests there may be an element of truth to this much-loved myth. 

As reported in the journal Atlantic Geology, researchers from the University of Oxford and Swansea University have recently been studying the Gough Map, a famous Medieval map of Britain, and discovered that it appears to depict two mysterious islands off the west coast of Wales. 


You can view the Gough Map at this link here.

No one is sure who made the map, how it was created, or even when it was published, although most current estimates say it was made around the 13th or 14th centuries CE. The Gough Map is a little sketchy on details (to say the least), but it’s one of the earliest maps to show Britain in a geographically-recognizable form.

“The Gough Map is extraordinarily accurate considering the surveying tools they would have had at their disposal at that time,” Simon Haslett, study author and an honorary professor of physical geography at Swansea University, told the BBC.

“The two islands are clearly marked and may corroborate contemporary accounts of a lost land mentioned in the Black Book of Carmarthen.”


Along with analyzing the map, the researchers also looked at coordinates recorded by the Roman cartographer Ptolemy, which suggested the Welsh coastline at the time was some 13 kilometers (8 miles) further west than it is today.

With these two strands of evidence, the duo believes they have found the murky origins behind the tale of Cantre'r Gwaelod.

It’s difficult to know where fact and fiction begin and end, but it’s possible to argue that Cardigan Bay was once home to two sunken islands whose fate became embellished in local folklore. 

The researchers believe that these two islands may have been made of silt and clay left behind from the end of the last ice age around 10,000 years ago. Eventually, these soft glacial deposits eventually became washed away from water erosion, storms, and so on. 


Cantre'r Gwaelod has inspired dozens of poems, songs, and stories over the centuries. According to the legend, the kingdom was made up of as many as sixteen cities governed by a supposed rule named Gwyddno Garanhir.

So the story goes, the king's friend Seithennyn was tasked with shutting the settlement’s sea gates each night. However, Seithennyn had a few too many drinks at the king’s palace one stormy evening and forgot to complete his duty, causing the islands to flood. 

Whether these two islands were genuinely home to a grand old kingdom seems extremely unlikely given the lack of reliable physical evidence. 

However, countless human cultures from around the world contain a mythological story featuring the archetypes of a great flood and a long-lost sea civilization. It’s been argued that these stories are the collective memory of the colossal floods that followed the end of the last ice age when giant ice-dammed lakes in Eurasia and North America gave way and filled the land with waves. 


Just like China’s Gun-Yu flood myth and the Genesis story of Noah’s arc, perhaps the legend of Cantre'r Gwaelod is just another re-imagining of a historic sea flood.

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