18 July 2025 The Future is the Product of the Past

Archaeologists discovered a sunken prehistoric fort in Clew Bay island

A sunken prehistoric fort has been discovered on Clew Bay island off the north Mayo coast, Ireland.

It has been reported that the discovered fort may be as important as Dún Aonghasa, the largest of the prehistoric stone forts of the Aran Islands. It is located on Inis Mór, at the edge of a 100-meter-high (330-foot) cliff. Dún Aonghasa (unofficial anglicized version Dún Aengus), a popular tourist destination, is a significant archaeological site.

Archaeologist Michael Gibbons told the Irish Independent that initial surveys suggested that the island of Collanmore was a late Bronze Age fort.

The discovery of several large ramparts slicing through the tidal isthmus connecting the island to the shoreline outside of Westport provided the first clue.

One of the bigger islands in the bay, Collanmore, which is accessible by foot at very low tides, was once a base for the Glenans Irish Sailing Club.

The set of double ramparts are faced with large limestone blocks and extending for 200 to 300 meters, and are “most likely to be late Bronze Age in date, dating between 1100-900 BC”, Mr Gibbons said.

Both features are covered on high tide, and the site is “so large and coated in seaweed that one can see why it wasn’t discovered before”.

Walls of the sunken fort are revealed in low tide in Clew Bay. Photo: Irısh Independent
Walls of the sunken fort are revealed in low tide in Clew Bay. Photo: Irısh Independent

The archaeologist said they were lucky that day as there were men cutting seaweed in the same area. A team from Connemara and archaeologists from Mayo County Council were also present.

“This outer rampart — as in, the one nearest the mainland — was known to the locals, but they had no idea how old it was or how significant it is. Their size and scale “would suggest that the island was of major strategic importance at the time”.

Gibbons stated that similar ramparts can be seen in other coastal and lake promontory forts in the west of Ireland, with the closest examples being found to the north, including a large promontory fort defended by double ramparts north of Newport, Co Mayo, and a massive promontory fort on Lough Fee, located on the northern shores of Carra Lake.

“Late Bronze Age hillforts are the largest monuments built in Ireland and can measure up to 320 acres in area, with kilometers of defensive ramparts,” he said.

The later part of the Bronze Age (1500-700 BC) was a time of settlement expansion and economic prosperity in Ireland. Hillforts are another manifestation of a warrior culture that emerged not only in Ireland but across Europe during the Middle and Late Bronze Age.

“They were built by warlord-dominated societies and we have very good evidence they were in active use during periods of warfare between various tribes,” Gibson added.

The Clew Bay discovery has been reported to the National Monuments Service.

Cover Photo: Clew Bay, Co, Mayo, Wikipedia

Related Articles

One of the earliest water channels in history dating back 8,200 years was discovered in western Türkiye

27 August 2023

27 August 2023

One of the earliest water channels in history dating back 8,200 years was found during the excavation work carried out...

Electoral inscriptions just discovered in Pompeii reveal clientelism in ancient Rome

29 September 2023

29 September 2023

Several electoral inscriptions, the ancient equivalent of today’s electoral posters and pamphlets, have appeared on the walls of the room...

Maya Farmers May Have Planned Population Growth Contrary to Thought

19 November 2021

19 November 2021

Contrary to what was thought, Maya farmers may have planned for population growth, says a new study. According to a...

Forged 5,000 Years Ago: The World’s Oldest Swords Discovered at Arslantepe Mound, Türkiye

10 June 2025

10 June 2025

In the arid plains of Eastern Anatolia, nestled along the western bank of the Euphrates River near Malatya, Turkey, lies...

Restoration of Türkiye’s 2,000-year-old King’s Daughter Roman bath nears completion

1 August 2023

1 August 2023

The 2,000-year-old Roman bathhouse Basilica Therma or King’s Daughter in Türkiye’s central Yozgat province is nearing the final stages of...

Google Earth Helped Archaeologists Make İmportant Discoveries in Leicestershire

26 April 2021

26 April 2021

After Google Earth revealed traces of underground structures, archaeologists digging at a Roman settlement in Leicestershire say they have made...

The discovery of a 380-million-year-old heart sheds new light on our bodies’ evolution

16 September 2022

16 September 2022

Researchers from Curtin University have discovered the world’s oldest heart in a ‘beautifully preserved’ ancient jawed fish fossil 380 million...

Ancient tools discovered in Maryland show the first humans came to America 7,000 years earlier than previously thought

23 May 2024

23 May 2024

When and how humans first settled in the Americas is a subject of considerable controversy. A Smithsonian Institution geologist now...

Two Altars Used for Blood Sacrifices and Divinations Discovered in the Ancient Thracian City of Perperikon

14 September 2024

14 September 2024

In the ancient Thracian city of Perperikon, partly carved into the rock in the Eastern Rhodope Mountains of Bulgaria, two...

The marble head of God Apollo unearthed in an excavation at Philippi, Greece

29 March 2024

29 March 2024

The excavation, carried out by a group of students of the Aristotle University of Thessaloniki in the archaeological site of...

Historical Armenian church 500-year-old in southeastern Turkey set to be restored

6 February 2022

6 February 2022

Work has been initiated to transfer the historical Armenian Church, which was built in the 16th century in the province...

Mystery of the ‘Deserted Castle’ Unraveled: Austria’s First Roman Bridgehead Fort Discovered

18 April 2025

18 April 2025

Researchers have identified the first confirmed Roman bridgehead fort in Austria, located near Stopfenreuth on the Lower Austrian Danube floodplains....

Ancient coins surface with Lake Iznik’s withdrawal in Türkiye

2 May 2023

2 May 2023

With the withdrawal of Lake Iznik in the northwest of Türkiye, the ancient coins found at the bottom of the...

Three Strange Skull Modifications Discovered in Viking Women

31 March 2024

31 March 2024

In recent years, research has provided evidence for permanent body modification in the Viking Age. The latest of these investigations...

2,000-year-old unique luxury Roman villa with “underfloor heating” found in Germany

3 November 2022

3 November 2022

A luxury Roman villa with a thermal bath and underfloor heating has been unearthed in Kempten, Bavaria, one of the...