Guide · Oct 20, 2026

The Baltic Sea UFO: What's Actually Known About the Anomaly

In 2011 a Swedish dive team's sonar caught a round shape on the floor of the Gulf of Bothnia. Here's what the image shows, what the rocks showed, and what's still only a claim.

By the UAP Press editorial team · Last updated Oct 20, 2026

Photo: the Gulf of Bothnia between Sweden and Finland, seen by NASA's Terra satellite on March 15, 2002. The anomaly is said to lie somewhere on this sea's floor. This isn't a picture of the object itself. Image by Jacques Descloitres, MODIS Land Rapid Response Team, NASA GSFC, public domain.

Short answer: The "Baltic Sea UFO" is a roughly 60-meter round shape on a blurry sonar image that a Swedish treasure-hunting team, Ocean X, recorded in the Gulf of Bothnia in June 2011. The team has said it looks man-made. Outside sonar experts said the image was too distorted to tell much from, and the geologist who examined rocks the team brought up found ordinary rock of the kind glaciers left all over the region. No one has shown it's a craft of any kind.

What's documented: One side-scan sonar image, a handful of dive photos released by the team, and rock samples that a Stockholm University geologist looked at in 2012. Everything else, from failing electronics to "burnt" stones, comes from the team's own accounts.

Status: Unresolved in the plain sense: no independent survey of the object has been published. A new survey ran in 2025, and Ocean X co-founder Dennis Åsberg said in mid-October 2026 that he was heading back out, weather permitting. As of October 20, 2026, we couldn't find a public report, dataset or paper from the 2025 survey, or any public result from the planned October trip.

Last checked: October 20, 2026, against the Society for UAP Studies website, Åsberg's public posts and a news search.

What did Ocean X find in 2011?

Ocean X is a Swedish diving and salvage outfit run by Peter Lindberg and Dennis Åsberg. In June 2011 they were towing a sonar in the northern Baltic, between Sweden and Finland, looking for an old shipwreck. What came back was a round shape about 60 meters (roughly 200 feet) across, sitting at the end of a long strip of smooth-looking seafloor. Press reports put it at roughly 90 meters (about 300 feet) down.

Lindberg first floated the idea that it could be an underwater "Stonehenge," Popular Mechanics reported that summer. The internet quickly went further. The long strip became a "runway" or skid mark, and the round shape became a flying saucer that had crashed and slid to a stop. The comparison that stuck was the Millennium Falcon from Star Wars.

Coverage came in waves, but the story went truly global after the Daily Mail ran it in June 2012, and the wilder theories took off from there. Since then it's been called the Baltic Sea anomaly, the Baltic Sea UFO, and sometimes a USO, an unidentified submerged object.

Why a sonar picture isn't a photograph

This is the part most write-ups skip, and it's the heart of the case.

Side-scan sonar is a device towed behind a boat. It sends sound out to both sides and records the echoes, line by line, as the boat moves. It's cheap and good at spotting shipwrecks, but it doesn't give you a 3D picture and it doesn't directly measure depth. The image is built from echoes, not light.

Hanumant Singh, then at the Woods Hole Oceanographic Institution, looked at the Ocean X image for Popular Mechanics and listed three problems:

A ghost on the other side. You can see a faint copy of the round shape in the opposite channel. The two sides of the sonar shouldn't affect each other. Singh called it "cross-talk," a sign the instrument wasn't wired properly.
Dropouts. Black horizontal lines run across the image, where the sonar wasn't picking up a return at all.
Gray edges. Beyond the shape, the image fades to gray, meaning the sonar couldn't tell what was there. To Singh, that showed it wasn't calibrated well enough to trust.

He added that the key, when something interesting shows up, is to turn the boat around and scan it again. The magazine reported that the team apparently hadn't done that. "I've been fooled hundreds of times [when using side-scan sonar] into thinking I've found something, when it's just a rock outcrop or a school of fish," he said.

Two more experts made the same point in other words. Dan Fornari, a marine geologist at Woods Hole who specializes in sonar surveys of the seafloor, told Live Science the image had "numerous artifacts" and that "the data are lacking in resolution, detail and quantification."

Live Science also noted that the white outline making it look like the Millennium Falcon had been added by the Ocean X team. Jonathon Hill, who analyzes Mars surface images at Arizona State University, didn't think much of that. "Drawing a picture of the Millennium Falcon over the sonar image? That only forces your imagination to see patterns that almost certainly don't really exist," he said. He also thought the sharp top edge of the "track" was an edge effect, a common artifact in this kind of imagery.

If you've ever wondered why nearly every famous UFO image is a smudge, it's the same problem. We go through it in why UFO photos are always blurry.

What did the 2012 dives report?

Ocean X went back in 2012 with divers and cameras. What came out of that season was mostly the team's description, not data.

A team diver, Stefan Hogeborn, said in an Ocean X press release that "anything electric out there, and the satellite phone as well, stopped working when we were above the object," and came back on once they were about 200 meters away. Lindberg said they'd found a second, similar shape about 200 meters from the first but wouldn't release that image because it was too blurry.

The divers also described "charred" or soot-covered stones and an egg-shaped opening in the top. "Normally, stones don't burn," Hogeborn said. Lindberg said that since no volcanic activity had been reported in the Baltic, "the find becomes even stranger."

Experts weren't persuaded. Fornari called the description of charred rocks "completely unwarranted." Katherine Croff Bell, chief scientist of the Nautilus Exploration Program, said nearly all rocks that have been underwater a long time are black, so the color alone doesn't point to fire or volcanoes. Live Science also noted that the press release had no photo of the "entrance."

Lindberg had also told the press he hoped to take "wealthy tourists" down in a submarine to see the site. Hill's advice on that was blunt: when someone makes an extraordinary claim, ask whether they're benefiting from it.

Later, in an hour-long radio interview that Live Science covered in August 2012, Lindberg talked about "very strange stair formations" and said, "If this is Atlantis, that would be quite amazing."

What did the rock samples show?

This is the one piece of the story that someone outside the team actually tested.

Ocean X gave rock samples from the site to Volker Brüchert, an associate professor of geology at Stockholm University. Swedish tabloids quoted him as saying he'd found a black stone that could be volcanic, which was read as support for the mystery. When Live Science asked him directly, he played it down. "What has been generously ignored by the Ocean-X team is that most of the samples they have brought up from the sea bottom are granites and gneisses and sandstones," he wrote.

Those are exactly the rocks you'd expect on the floor of a basin carved by ice sheets, which the Baltic is. The one piece of basalt was loose. It was out of place, he said, but not unusual. "Because the whole northern Baltic region is so heavily influenced by glacial thawing processes, both the feature and the rock samples are likely to have formed in connection with glacial and postglacial processes," Brüchert wrote. "Possibly these rocks were transported there by glaciers."

Other scientists weighed in too, as summarized on Wikipedia. Swedish geologists Fredrik Klingberg and Martin Jakobsson said the iron minerals reported in the samples, limonite and goethite, can form naturally. Göran Ekberg, a marine archaeologist at Stockholm's Maritime Museum, said a natural formation couldn't be ruled out: "nature has produced stranger things than that." A Finnish planetary geomorphologist, Jarmo Korteniemi, later said the "runway" was most likely a drumlin, a ridge shaped by glacial ice.

One caveat cuts both ways. Accounts differ on whether the samples came from the structure itself or from the seafloor around it, and nobody has published a test of a core drilled from the structure.

The claims next to what was checked

Claim	Who says it	What's been checked
It's a 60 m disc with a "runway" behind it	Ocean X, from the 2011 sonar image	Experts said the image had cross-talk, dropouts and edge effects, and that the outline was drawn on
Electronics fail above it	Ocean X divers, 2012	No times, instruments or measurements published
The stones are burnt	Ocean X divers, 2012	Experts said old underwater rocks are usually black; no published lab result shows fire
The rock is volcanic, so it doesn't belong	Ocean X, tabloids	Geologist found mostly granite, gneiss and sandstone, plus one loose basalt piece, consistent with glacial transport
Stairs, right angles, corridors	Ocean X, 2012 to 2025	No scaled, independent survey published
It's not attached to the seabed	Åsberg, 2025	Based on the team's 2025 data; no public report found
Parts of it "look artificial"	Åsberg, January 2026	Two low-resolution multibeam images posted; the rest of the data is being held back

Is there a real photo? And where is it?

Those are two of the most searched questions, so here's a straight answer to each.

The only image of the whole object is the 2011 sonar scan. The team later released close-up dive photos of rocks and surfaces. The striking picture of an Atlantis-like ruin on the seabed that gets shared everywhere is an illustration by a graphic artist, not a photograph. Live Science labeled it that way in 2012.

As for a map, there isn't a reliable one. Ocean X hasn't publicly released the coordinates. Reports place it in the Gulf of Bothnia, the northern arm of the Baltic between Sweden and Finland. Any pin you see online is a guess.

What's the latest?

In July 2025, the Society for UAP Studies said it was supporting a new survey of the site. It wasn't leading the work. It said the first phase used multibeam sonar, sub-bottom profilers, 3D photogrammetry and environmental sensors, and that a public report would follow once the data was reviewed. That's the right toolkit. Multibeam sonar maps shape and depth far better than the 2011 side-scan did.

In November 2025, Åsberg went on the American Alchemy podcast with Jesse Michels. According to the episode notes, he said a 2025 sub-bottom profile suggests the object is detached from the seabed. He also described right-angle geometry, GPS failures, biological material, burned debris, basalt and water near 0°C right above the structure. A few news sites repeated these points as "new evidence."

Here's what has surfaced in 2026, all of it from Åsberg's own posts on X:

January 9, 2026: He posted two multibeam sonar images from the 2025 survey. He called them "only a very small part of the data," said they aren't high-resolution, and said he's holding back the rest until a full scientific report is ready. He also wrote that "parts of it look artificial."
March 31, 2026: He posted a sonar image of a second object, which he calls A2, lying about 200 meters from the main one, and said the team planned to work on both in summer 2026.
October 16, 2026: He wrote that the summer's plans had run into "setbacks, technical problems, weather issues," and that the team hoped to head back out on Monday, October 19, if the weather allowed. He said the main goal this time is photogrammetry, and added, "I'm not promising some extraordinary discovery."

These are claims and plans from the people who found the feature, not findings anyone else has checked. As of October 20, 2026, we couldn't find the report the Society for UAP Studies promised, a released dataset or a peer-reviewed paper, and we found no public result from the October trip. If one appears, the multibeam maps, sub-bottom profiles and photogrammetry models are what to look at first.

What would settle the Baltic Sea anomaly?

It wouldn't take anything exotic. Released coordinates, raw sonar files and a survey by an independent team would let geologists test the glacial explanation directly. So would a core sample taken from the structure itself, not the rocks around it.

Until then, the honest read is that a low-quality sonar picture showed a roundish feature on a seafloor full of glacial debris. The outside experts quoted on the record pointed to natural explanations or said the data couldn't support any conclusion. The team still says it's something unusual. Neither side has produced the kind of data that would end the argument.

For a land-based case where a crash story grew far beyond the original evidence, see what actually happened at Roswell. For what the U.S. government has put on the record about unresolved sightings, start with the Pentagon UFO files. And if you're curious why "UFO" gave way to "UAP," we explain it in why UFO became UAP. If you see something you can't explain yourself, here's how to report a UAP sighting.

Sources

Frequently asked questions

What is the Baltic Sea anomaly?

It's a round feature about 60 meters across on the floor of the Gulf of Bothnia, recorded on a side-scan sonar image by the Swedish dive team Ocean X in June 2011. The team says it looks man-made. Outside experts said the image was too distorted to identify anything, and rocks from the site turned out to be ordinary glacial stone.

Is the Baltic Sea UFO real?

The sonar image is real, and there's something on the seafloor. What hasn't been shown is that it's a craft of any kind. A Stockholm University geologist found mostly granite, gneiss and sandstone in the samples and said glaciers probably shaped the feature.

Is there a real photo of the Baltic Sea anomaly?

The only image of the whole object is the 2011 sonar scan, plus close-up dive photos of rocks that the team released later. The widely shared picture of an Atlantis-like ruin is an artist's illustration, not a photograph.

Where is the Baltic Sea anomaly located?

Reports place it in the Gulf of Bothnia, the northern arm of the Baltic Sea between Sweden and Finland, at a depth of roughly 90 meters. Ocean X hasn't publicly released the exact coordinates, so online maps are guesses.

What is the latest news on the Baltic Sea anomaly?

A new survey using multibeam sonar and sub-bottom profilers ran in 2025 with support from the Society for UAP Studies. Ocean X co-founder Dennis Åsberg has since posted two low-resolution multibeam images (January 2026) and said in mid-October 2026 that the team was heading back out, weather permitting, to do photogrammetry. As of October 20, 2026, we couldn't find a published report or dataset backing up the team's claims.

Why did electronics fail near the Baltic Sea anomaly?

That's the team's account. A diver said in a 2012 press release that the satellite phone and other gear stopped working over the object and came back about 200 meters away. No times, instruments or measurements were published, so it hasn't been independently checked.