Massive Underground Formation Found Beneath Bermuda Baffles Scientists

A new geological discovery beneath Bermuda is drawing fresh scientific attention to the North Atlantic, shifting focus away from old myths and toward a far more intriguing natural mystery. Researchers have identified an unusually thick rock layer—about 20 kilometers (12.4 miles)—hidden beneath the oceanic crust below the Bermuda archipelago. No similar structure of this size has been documented anywhere else on Earth.

According to William Frazer, a seismologist at Carnegie Science in Washington, D.C. and lead author of the study, the finding challenges long-standing assumptions about oceanic geology. Normally, the oceanic crust transitions directly into Earth’s mantle. In Bermuda’s case, however, scientists found an unexpected intermediate layer embedded beneath the crust and within the tectonic plate that supports the island.

A Possible Explanation for Bermuda’s Elevated Seafloor

Although the exact origin of this hidden layer remains uncertain, it may help resolve a long-standing puzzle: why Bermuda sits atop an elevated region of ocean floor known as an oceanic swell. Typically, such swells are associated with active volcanic processes, yet Bermuda has shown no volcanic activity for roughly 31 million years.

Frazer suggests that the island’s final volcanic phase may have forced mantle material upward into the crust, where it cooled and solidified. This dense intrusion could act like a geological “float,” lifting the surrounding seafloor by approximately 500 meters (1,640 feet) and preventing it from sinking over time.

Beyond the Bermuda Triangle Myth

While Bermuda is widely known for the legend of the Bermuda Triangle—an area historically associated with unexplained ship and aircraft disappearances—scientists emphasize that those stories are largely exaggerated. The real mystery lies beneath the surface: why the island’s oceanic swell has persisted for millions of years without ongoing volcanism.

In contrast, island chains such as Hawaii form above mantle hotspots, where rising heat creates continuous volcanic activity. As tectonic plates move away from these hotspots, the seafloor typically cools and sinks. Bermuda, however, defies this pattern.

Seismic Imaging Reveals the Hidden Layer

To investigate what lies below Bermuda, Frazer and co-author Jeffrey Park, a professor at Yale University, analyzed seismic data recorded on the island from powerful earthquakes occurring across the globe. By studying how seismic waves changed as they passed through Earth’s interior, the researchers were able to map geological structures down to a depth of about 50 kilometers (31 miles).

Their analysis revealed the presence of a thick, relatively low-density rock layer beneath the crust—an anomaly that likely plays a role in maintaining Bermuda’s elevated position.

The research was published on November 28 in the journal Geophysical Research Letters.

Ancient Carbon From Deep Within Earth

Independent research supports the idea that Bermuda’s geology is unique. Sarah Mazza, a geologist at Smith College who was not involved in the study, noted that remnants of ancient volcanic material beneath the island may still be contributing to its elevation.

Mazza’s previous work found that Bermuda’s lava is unusually low in silica, indicating an origin from carbon-rich mantle material. Her analysis of zinc isotope variations, published in September in the journal Geology, suggests that this carbon was transported deep into the mantle hundreds of millions of years ago—likely during the formation of the supercontinent Pangea, between 900 and 300 million years ago.

This process differs significantly from what is observed beneath volcanic islands in the Pacific and Indian oceans. Scientists believe the difference may be linked to the Atlantic Ocean’s relatively young age, as it formed when Pangea broke apart, unlike the older ocean basins that existed along Pangea’s margins.