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At 120 meters deep in the Mediterranean Sea, near the island of Corsica, a team led by explorer Laurent Ballesta mapped over 1,400 giant circles drawn in the sand with surprising geometric precision — and science still has no definitive explanation for them.
According to Exame and Revista Oeste, the Mediterranean circles were revealed to the public in May 2026.
Laurent Ballesta, National Geographic photographer and explorer, led the expeditions. He documented the formations with high-resolution sonar and technical dives to 120 meters deep.
Therefore, the discovery came with two mysteries at once. The first: where did these highly regular patterns come from in a naturally irregular environment.
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The second: why carbon dating indicates the formations are 21,000 years old — a time when the Mediterranean was very different from what it is today.
The Mediterranean circles in numbers: what Laurent Ballesta found
The dimensions are hard to ignore.
Each circle is tens of meters in diameter, and the set occupies an area of 250,000 square meters — equivalent to about 25 football fields covered by repeated geometric patterns.
Furthermore, the precision is what most baffles scientists.
According to Oficina da Net, the rings show well-defined edges and consistent spacing — something “rarely seen in ocean exploration” in a natural sandy seabed environment.
Similarly, the quantity is impressive. There are over 1,400 formations — not one or two isolated structures, but a pattern covering a vast area of the seabed.
Thus, the hypothesis of a random event becomes difficult to sustain.
- 1,400+ circles documented near Corsica, Mediterranean
- 120 meters deep — beyond the reach of conventional divers
- 250,000 m² total area — equivalent to 25 football fields
- 21,000 years estimated age by carbon dating
- Tens of meters in diameter for each individual ring
The precision that left researchers without an immediate answer
What most intrigues researchers is not just the size of the Mediterranean circles, but their regularity. In a marine environment at 120 meters, currents and organisms normally create chaotic patterns.
In this regard, the French newspaper Le Parisien described: “Not every underwater phenomenon finds an immediate explanation. The scale and precision of the circles place them in a category rarely seen in ocean exploration.”
Therefore, scientists have been working with two main hypotheses to explain the origin of the formations. Both have evidence in their favor — and neither is definitively confirmed.
The depth of 120 meters was, for a long time, a natural barrier for conventional scientific expeditions.
Recreational divers safely reach a maximum of 40 meters. Therefore, Ballesta’s documentation required specialized technical equipment and months of preparation.
In addition, high-resolution sonar was crucial. Without this feature, the formations appeared only as “clear discs” in the raw data — and were ignored by previous expeditions.
Consequently, the discovery also serves as a reminder that technology and curiosity sometimes arrive together at the same place, at the right time.
The two scientific hypotheses for the circles
The first hypothesis points to consistent currents and eddies over decades. According to marine geomorphology researchers, repetitive vortices on the seabed can sculpt rings in the sand with increasing precision over millennia.
However, the second hypothesis involves marine organisms. According to Exame, researchers evaluate that structures “resulting from organisms interacting with the sandy bottom in a recurrent way” could generate such regular patterns.
In other words, life on the seabed could be the artist.
Similarly, these formations evoke comparisons with other natural mysteries.
The fairy circles of the Namib Desert, attributed to ecological interactions between plants and insects, follow a similar logic — but on land, not on the seabed.
21,000 years ago: when the Mediterranean was another world
Carbon dating revealed that the circles began to form about 21,000 years ago — at the end of the last glacial period. Consequently, this historical context changes everything.
21,000 years ago, sea levels were tens of meters lower than today.
The stretch of the Mediterranean where the formations now lie at 120 meters was an area of shallower waters — or even coastal.
Thus, the process that created the circles happened in a completely different environment from the current one.
In addition, temperature and salinity conditions were distinct. Therefore, the correct explanation needs to account not only for what we see today, but for what was on that ocean floor more than two centuries ago.
Why the Mediterranean circles matter for ocean science
Investigations like Ballesta’s open doors to understanding patterns that may exist on other unmapped seabeds.
According to Exame, marine biology, geology, and ocean current dynamics scientists are studying whether similar formations exist in other regions of the Mediterranean.
In comparison, the seabed holds records that land does not preserve. As shown by the world’s deepest shipwreck at 6,800 meters in the Pacific, the ocean preserves structures for centuries.
As the discovery of the world’s deepest shipwreck at 6,800 meters in the Pacific showed, the ocean hides structures for centuries — or, in this case, millennia.
On the other hand, access to 120 meters requires equipment and techniques that few possess. Similarly, most of the planet’s ocean floor has never been mapped in high resolution.
So, how many fields of similar circles might exist — and have never been seen? Just as fossils in China revealed complex life much earlier than expected, the Mediterranean may hold more surprises.
Just as a set of fossils in China revealed complex life much earlier than expected, the Mediterranean seabed may hold more surprises.
Still, the most probable version is natural. The dating indicates an ancient geological or biological process.
However, until a peer-reviewed article confirms the winning hypothesis, the Mediterranean holds one of the most visual mysteries of ocean science in 2026.
Note: the data on the formations are based on May 2026 reports from Exame, Revista Oeste, and Oficina da Net.
Formal scientific studies on the origin of the circles are underway and have not yet been published in peer-reviewed journals.
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