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Many kilometers down on the seafloor in the Arctic, beneath thick, drifting sea ice – where no sunlight can reach, abundant life exists – against all odds. But why?

There, hydrothermal vents – hot springs on the seafloor where superheated seawater seeps out, rich in dissolved minerals and gases, fuel unique ‘oases’ ecosystems that survive on chemical energy contained in the hot waters.

In the last decades, deep sea scientists have collected samples from vents in many other parts of the world, but since the turn of the century, reaching a particular group of vents known to be hidden deep under polar ice became a “last frontier” in deep sea exploration.

Scientists have known for more than 20 years that along Earth's slowest-spreading mountain chain – the Gakkel Ridge – there is at least one vent site where ‘Aurora’ might be located. However, thick drifting sea ice has created enormous technical challenges and significant risks in reaching the site. If an underwater robot were to get stuck or trapped, the entire mission could be lost. 

In 2021, an international team of researchers – with several leading scientists from the University of Bergen – finally succeeded in this ‘moon landing’ with funding from the Norwegian Research council. Now these precious samples have been analyzed, and the first research findings are ready.

A significant scientific and technological feat under the ice

“It felt like landing on the Moon. Honestly, I think we underestimated how difficult it was going to be. But we did it – and it was an incredible moment,” says Professor Eoghan P. Reeves at the Department of Earth Science & Centre for Deep Sea Research, University of Bergen, about the expedition.

He explains that this was one of the most demanding ocean research expeditions ever carried out – no one had done this before. The team was aboard the then (almost) brand new icebreaker Kronprins Haakon and used a remotely operated vehicle to collect the very first mineral deposit and vent fluid samples from a hydrothermal vent field nearly 4 km under moving, permanent sea ice.

“In the ship’s conference room, everyone watching the video feed from the seafloor was just cheering with joy when we got the first views of the black smoker. But for those of us guiding the ROV and pilots, it was almost panic at that moment: how on earth were we going to land this thing in the right place?” he recalls. 

“I understood, in that moment, how stressed Neil Armstrong might have felt in the final minutes of Apollo 11. But we had done this in many cruises around the world, now we just had to keep calm, and work fast”. 

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Here is the research vessel Kronprins Haakon, which was used for the expedition.

Spectacular black smoker “chimneys” on the seafloor

The hydrothermal vents at Aurora look much like smoking chimneys, but with fluids of almost 350ºC rushing out of the seabed, they are loaded with metals, sulfur and gases. As soon as the hot fluids hit the icy seawater, dissolved minerals precipitate out and build chimney-like structures on the ocean floor. Footage of the vents from this expedition recently starred in the Netflix documentary series, Our Oceans, narrated by Barack Obama. 

These kinds of environments have long fascinated scientists, because they can tell us something about how life may have first emerged on Earth – and how, in the future, we might search for life on ice-covered ‘Ocean World’ moons such as Europa and Enceladus in our Solar System.

“There are many reasons why we study hydrothermal vents. Some people are interested in ore deposit formation - metals that could become important if deep-sea mining ever develops. Others, like me, are also interested in what they can tell us about the fundamental chemistry of life on Earth and maybe in our nearest neighbor worlds,” says Reeves, who just returned from sabbatical at the NASA Jet Propulsion Laboratory in LA.

Massive hydrogen release: “rocket fuel and candy” for life

“When we got the first samples from Aurora, that was really the proof that we could actually do this kind of deep sea exploration. But afterwards, the real scientific work began, back in the labs – that’s where the new findings are created and tested” Reeves says.
So what does the seabed under the Arctic ice actually look like? 

The findings show that the hydrothermal vents here are in fact different from vent systems elsewhere  – and much more extreme than the well-known Loki’s Castle vents farther south in Norwegian waters. 

“They are much much hotter, and richer in many different chemicals” says Reeves. 

“Just getting there to find familar chemicals would have been worth the feat, but we found brand new compositions – that really expanded our menu of black smoker flavors”

Analyses of the chimney samples reveal that the chimneys contain traces of elements like Ni and Co normally only find deep inside the Earth. 

“We discovered chimneys that were unusually fragile, and thin, with minerals we didn’t expect at all. The chemistry of the fluids was also special: they are extraordinarily rich in dissolved hydrogen gas,” Reeves explains.

In fact, the levels of hydrogen were over twice as high as at any other vent field studied so far.

He describes hydrogen as “rocket fuel and candy for microbes.” For microscopic life, such energy sources are worth gold in the barren desert of the deep sea – it’s energy they can thrive on.

The expedition also found new biological species and unusual coatings on the minerals, unlike elsewhere. Some of the structures were coated in calcium carbonate – unlike ordinary chimneys, almost like a protective film.

“We are seeing things there that don’t look like anything we’ve found before elsewhere. It means we need to rethink what we think is happening in these places, and – importantly, keep exploring down there” says Reeves.

Reference

Charles Lapointe, John W. Jamieson, Eoghan P. Reeves, Samuel I. Pereira, Hilary Corlett, Stefan Bünz, Eva Ramirez-Llodra: . Earth and Planetary Science Letters, 2025.