In the permanent darkness of the Norwegian Sea, a mile beneath the surface, something is breathing.

A remotely operated vehicle named Ægir 6000 descended to the wreck of the Soviet submarine Komsomolets in 2019 and captured video of pale plumes drifting from a ventilation pipe—visible exhalations of radioactive material escaping from the vessel’s corroding reactor. The footage, analyzed and published this week in Proceedings of the National Academy of Sciences, confirms what researchers have suspected for decades: the Komsomolets is still leaking.

The ghost of the Cold War has a pulse.

What the ROV Found

The research team, led by marine radioecologist Justin Gwynn of Norway’s Radiation and Nuclear Safety Authority, collected water samples from those plumes and discovered strontium and caesium levels that were, respectively, 400,000 and 800,000 times higher than typical background concentrations in the Norwegian Sea.

The ratios of uranium and plutonium isotopes tell a clearer story: the nuclear fuel inside the reactor is actively corroding. This isn’t residual contamination from the original disaster. The submarine’s heart is still breaking down.

“Releases from the reactor have occurred for over 30 years,” the researchers write. But—and this is crucial—“there is little evidence of any accumulation of radionuclides in the near environment around the submarine as the released radionuclides appear to be rapidly diluted in the surrounding seawater.”

A few meters from the hull, radiation levels drop sharply. The Norwegian Sea is vast, cold, and apparently forgiving.

The Disaster That Started It All

The Komsomolets was no ordinary submarine. Commissioned in 1983, it was a titanium-hulled prototype designed to dive deeper than any American vessel could follow. On April 7, 1989, during its third operational patrol, a fire erupted in an engineering compartment. The blaze spread through cable penetrations in the bulkheads. Temperatures soared past 1,000°C.

The crew surfaced. They fought the fire for hours. But compressed air from a cracked ballast tank pipe fed the flames like a blowtorch. The submarine sank at 15:15, taking 42 crew members with it. Only 27 survived the freezing waters.

The Komsomolets settled 1,680 meters down, upright on the seafloor. It carried its nuclear reactor and two nuclear-armed torpedoes into the abyss.

A Rare Success Story

Here’s where the story takes an unexpected turn. In the 1990s, despite an economy in freefall, post-Soviet Russia mounted an aggressive remediation effort. Manned submersibles sealed the torpedo compartment with titanium plugs and covered exposed areas with metal plating. The goal was straightforward: keep the warheads contained.

According to the new research, those patches are still holding. The 2019 survey found no evidence of weapons-grade plutonium leaking from the torpedo section. Svetlana Savranskaya, director of Russia programs at George Washington University’s National Security Archive, reviewed the study and described the Soviet cleanup as “an incredible effort, especially given the state in which the country was in the early 1990s.”

“Gorbachev and Yeltsin wanted to be seen as responsible international actors,” Savranskaya told Gizmodo. “They did learn lessons from Chernobyl—that secrecy is, really, not helpful in these situations.”

The marine life growing on the wreck—sponges, corals, anemones—shows slightly elevated caesium levels but no obvious deformities. The surrounding sediment is clean.

The Clock Is Still Ticking

Dilution is working. For now.

But titanium corrodes. Saltwater is patient. The reactor contains radioactive material that will remain dangerous for centuries, and the vessel’s structural integrity will only degrade further. The researchers note that the leak isn’t constant—it comes in sporadic bursts, and they don’t fully understand why.

Bringing the submarine to the surface would be astronomically expensive and deeply risky. One accident during a salvage operation could spread contamination far more widely than the current deep-sea leak ever will.

The Komsomolets will stay where it is. The question is how long “dilution is the solution” remains a viable strategy.

A Warning From the Deep

The researchers frame their findings as more than a single wreck’s status report. Komsomolets, they write, “provides a unique opportunity to understand the risks and consequences of releases from other sunken or dumped reactors in the Arctic.”

There are others. Soviet nuclear waste was dumped in Arctic waters throughout the Cold War. Other submarines have sunk. The full inventory of what’s down there—and what condition it’s in—remains incomplete.

The Komsomolets ghost story isn’t over. It’s just begun its second act.

Sources