A recent scientific breakthrough in the Arctic Ocean has pushed the boundaries of deep-sea research. During the Ocean Census Arctic Deep–EXTREME24 expedition, researchers uncovered an unexpected phenomenon at a depth of 3,640 meters. Published in Nature Communications, the findings are already reshaping how scientists think about the deep ocean’s role in climate, biodiversity, and geological processes.
A Geologically Dynamic World Beneath the Greenland Sea
The newly discovered Freya Hydrate Mounds, found along the Molloy Ridge in the Greenland Sea, lie at a depth nearly twice that of previously known hydrate outcrops. Until now, such systems were thought to be confined to shallower depths, typically less than 2,000 meters. This discovery pushes that limit by almost 1,800 meters, radically redefining what scientists believed about where and how gas hydrates form.
“This discovery rewrites the playbook for Arctic deep-sea ecosystems and carbon cycling,” said Giuliana Panieri, Professor at UiT and now Director of CNR-ISP, who led the expedition alongside Alex Rogers. “We found an ultra-deep system that is both geologically dynamic and biologically rich, with implications for biodiversity, climate processes, and future stewardship of the High North.”
Researchers observed methane gas flares rising more than 3,300 meters through the water column, among the tallest ever recorded globally. These flares are thought to be the result of thermogenic gas and crude oil emissions from deep Miocene-aged sediments, evidence of complex geological fluid migrations occurring far beneath the seafloor.
Life Thrives in the Deepest Cold Seep Known
Even more surprising was the diversity of chemosynthetic life flourishing around the seep. Organisms such as siboglinid tubeworms, maldanid worms, amphipods, and snails were observed clustered around the active seepage zones. These species rely on chemicals like methane and hydrogen sulfide, rather than sunlight, to survive, making them uniquely adapted to extreme, lightless environments.
“There are likely to be more very deep gas hydrated cold seeps like the Freya mounds awaiting discovery in the region,” said Jon Copley of the University of Southampton, who led the biogeographic analysis of the site. “The marine life that thrives around them may be critical in contributing to the biodiversity of the deep Arctic.”
What’s particularly compelling is the unexpected ecological overlap between the Freya mounds and hydrothermal vent communities found elsewhere in the Arctic. These similarities suggest that deep-sea ecosystems once considered isolated may actually be linked, creating a network of biodiversity “islands” on the Arctic seafloor.
“The links that we have found between life at this seep and hydrothermal vents in the Arctic indicate that these island-like habitats on the ocean floor will need to be protected from any future impacts of deep-sea mining in the region,” Copley emphasized.
An Active, Evolving Geological Feature
The Freya Hydrate Mounds are not relics. They are alive, geologically speaking. Researchers observed the mounds in various stages of growth and collapse, revealing a dynamic landscape that changes in response to tectonic activity, heat flow, and climate-related processes.
“These are not static deposits,” Panieri added. “They are living geological features, responding to tectonics, deep heat flow, and environmental change.”
This evolving nature makes the site a natural laboratory for studying methane behavior in the deep sea. With growing concerns about climate change and methane release from Arctic permafrost and ocean floor systems, these findings could help refine models of deep carbon cycling and methane sequestration in polar regions.
ROV imaging technology played a key role in documenting the seafloor environment, capturing high-resolution footage of hydrate structures, seeping fluids, and the life they support. This data offers an unprecedented look into the physical and biological dynamics of one of Earth’s most extreme and remote ecosystems.
Urgent Questions for Arctic Policy and Conservation
Situated in international waters of the Arctic Ocean, the Freya Hydrate Mounds highlight the urgent need for responsible environmental policy. With growing interest in resource extraction from the deep sea, the discovery adds weight to calls for precautionary governance and evidence-based decision-making.
“Understanding these unique habitats is essential for safeguarding biodiversity and supporting responsible decision-making in polar regions,” Panieri said.
The study, published in Nature Communications, reflects a significant step forward in Arctic science and illustrates how multinational cooperation and advanced ocean technology are essential to uncovering and protecting Earth’s last frontiers.