Could a stone wall beneath the waves be the echo of a lost civilization from 10,000 years ago? Off Spain’s Salmedina Island, a sprawling network of submerged stone structures-some rising 23 feet high and stretching 6.5 feet thick-has ignited fresh debate over Plato’s fabled Atlantis. Independent researcher Michael Donnellan, who has spent a decade diving, filming, and mapping the site, believes these ruins could be the remnants of what he calls an “Ancient Atlantic Culture,” a society that may have thrived thousands of years before the Phoenicians, Tartessians, or Romans.
The site is located west of the Strait of Gibraltar, in waters where the stone slabs surface only twice a day at low tide. Geological depth measurements suggest the structures sit more than 20 meters below the seabed, buried under additional layers of sediment. Material found as shallow as 3 meters deep can date back 3,000 years in this region, so Donnellan’s team estimates the ruins could be 10,000 to 12,000 years old, placing them in the epoch just after the last Ice Age.
Evidence suggests it met a violent end. Salmedina lies close to the Azores-Gibraltar Transform Fault, which can generate massive earthquakes and tsunamis, including the 1755 Great Lisbon Earthquake. Cores taken from the sea floor on the site reveal chaotic, unstratified sediment deposits, hallmarks of sudden cataclysmic events rather than gradual accumulation. “There’s every indication these settlements were affected by a really traumatic impact or a series of climatic changes,” Donnellan says.
Advanced marine archaeology equipment was used by the research team to study the ruins. LiDAR scanning and multibeam echosounders made 3-D maps of the ocean floor, showing the exact placement of walls and platforms. This kind of technology, like the next-generation subsea lidar systems that oceanographic institutes use, lets researchers capture centimeter-scale detail even in tough underwater conditions. That precision has been important in comparing the site’s geometry with Plato’s descriptions of Atlantis capital with concentric rings of land and water, and elaborate harbors and monumental architecture.
The parallels are striking enough to recall other moments when myth became history. In the 1870s, Heinrich Schliemann used Homer’s epics to locate Troy, uncovering fortifications once thought imaginary. Donnellan sees a similar possibility here: “Either Plato was talking about this very place, or it’s a tremendous coincidence that science and Plato’s texts are coming together.”
Other researchers are more circumspect in their fascination. Anthropologist José “Pepe” Orihuela observed that megalithic phenomena indeed flowered during the Holocene in western Europe, with the Gulf of Cádiz as one of its cultural epicenters. This makes sense in the context of the theory of a sophisticated coastal society whose memories inspired the Atlantis legend. However, some geologists, such as Juan Antonio Morales, describe how they may be natural, their shapes formed by geological rather than human forces.
The allure of the find is magnified by recent discoveries across the Iberian Peninsula and into the Atlantic: from ring-shaped ruins beneath Cádiz’s marshes to submerged walls offshore of Doñana National Park, imaging advances have revealed patterns that echo ancient texts. In each case, the possibility of massive floods or tsunami events known to have reshaped these coasts permeates the theory that whole settlements could be erased in a geological instant.
For Donnellan’s team, the site at Salmedina is only a part of the bigger picture. “The ruins we’ve discovered under the water are only a small fragment of the entire series of discoveries,” he says. Their efforts will continue both on land and at sea, in hope of piecing together a fuller picture of a civilization which-if confirmed-would push back the timeline of advanced human culture by millennia.
Whether these stones constitute the remains of Atlantis or another lost society, they serve as a reminder that the dividing line between legend and history is never fixed. As technology peels back the layers of the ocean floor, stories once relegated to myth may reveal themselves in the quiet geometry of ancient walls, waiting for the tide to draw them into view.
