10 Things You Didn’t Know About Santorini and Its Volcano

When most people think of Santorini, they picture whitewashed houses tumbling down cliffs, blue-domed churches glistening under the Aegean sun, and sunsets so dramatic they stop you in your tracks. But behind the island’s postcard beauty lies one of the most powerful geological stories in the world. Santorini isn’t just an island. It is the product of one of the largest volcanic eruptions in human history, a place where fire and earth reshaped the sea, and where a sleeping giant still breathes beneath the surface.

The caldera you see today, that massive crescent-shaped cliff surrounding the sea, was formed through cycles of eruptions, collapses, and regrowth over thousands of years. This is the hidden side of Santorini, one that most travelers don’t think about while sipping wine in Oia. To understand the island fully is to understand its volcano. Here are 10 things you probably didn’t know about Santorini’s volcano and caldera.

1. The Eruption That May Have Inspired Atlantis

Around 1600 BC, one of the largest volcanic eruptions in human history tore Santorini apart. Known as the Minoan eruption, it released more than 60 cubic kilometers of magma, blasting ash and pumice high into the atmosphere. The force collapsed the center of the island into the sea, forming the caldera we see today.

This eruption didn’t just change Santorini. It devastated the Minoan civilization on nearby Crete, burying cities in ash and possibly causing tsunamis that traveled across the Aegean. Some archaeologists believe this catastrophic event inspired Plato’s story of Atlantis, the “lost city” swallowed by the sea. Whether or not that’s true, the eruption left a permanent mark on history and created the landscape that continues to fascinate millions of visitors each year.

2. The Caldera is Still Active

Santorini’s volcano isn’t a relic of the past, it’s very much alive. In the middle of the caldera sit two small islands, Nea Kameni and Palea Kameni, formed by eruptions over the last 2,000 years. The most recent major eruption occurred in the 1950s, when Nea Kameni spewed ash, lava, and smoke. Villages on Santorini were blanketed in ash, and tremors shook the ground.

Even today, visitors who hike across Nea Kameni can see steaming fumaroles, cracks in the earth that release sulfurous gases. Scientists constantly monitor seismic activity, ground temperature, and gas emissions here. The volcano is considered “dormant,” not extinct, meaning it could erupt again. The beauty of Santorini is literally built on restless ground.

3. You Can Walk on an Active Volcano

One of the most surreal experiences you can have in Greece is hiking across Nea Kameni. A short boat ride from Santorini takes you to the rocky, barren island, where trails wind past black lava fields and sulfur vents. It feels like stepping onto another planet.

Guides explain how each section of the island was formed by different eruptions, with the youngest lava flows only decades old. At the summit, you can look down into craters and see steam rising from the earth. Then, just minutes away, you can swim in hot springs warmed by the volcano itself. It’s not often you can say you stood on an active volcano in the middle of the sea.

4. The Caldera is One of the Most Closely Monitored in the World

Because of its explosive history, Santorini’s volcano is constantly watched by the Institute for Geodynamics in Athens and other scientific organizations. Seismographs measure tremors, satellites track ground movement, and gas sensors detect changes in emissions.

This became especially important in 2011–2012, when scientists detected unusual activity, small earthquakes and swelling of the ground beneath the caldera. For months, speculation grew about whether the volcano might erupt again. Ultimately, the activity calmed down, but it was a reminder that Santorini is not just a tourist paradise, it is a living geological system.

5. Santorini’s Wine Exists Because of the Volcano

The island’s famous wines, especially Assyrtiko, owe their unique flavor to the volcanic soil. Santorini’s earth is made up of volcanic ash, pumice, and lava rock, creating a soil that retains very little water but is rich in minerals. Vines have to dig deep to survive, resulting in concentrated grapes with distinct minerality.

The traditional way of growing grapes here is just as unique. Farmers weave the vines into low, basket-shaped coils called kouloura to protect them from strong winds. The combination of volcanic soil, salty sea breezes, and this special cultivation method produces wines unlike anywhere else in the world. Without the volcano, Santorini’s wine industry would not exist in its current form.

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6. The 1950s Eruption Changed Daily Life

Many people don’t realize that living memory of eruption still exists in Santorini. In 1950, Nea Kameni erupted, sending lava and ash into the air. Though small compared to the Minoan eruption, it was disruptive. Villagers recall skies filled with smoke, ash covering crops, and the smell of sulfur in the air.

Life on Santorini was already difficult in the mid-20th century, with poverty and emigration common. The eruption added another layer of hardship, reminding residents that beauty comes with risk. For older generations, the volcano was never just a tourist attraction, it was a real, sometimes dangerous neighbor.

7. Hot Springs Bubble at the Edge of the Caldera

One of the most unusual experiences near the volcano is swimming in the hot springs off Palea Kameni. The water here is heated by geothermal activity beneath the surface, creating pockets of warmth in the otherwise cool Aegean. The springs are rich in iron and sulfur, turning the water a rusty orange and said to have healing properties.

Boats drop anchor nearby, and visitors swim through cooler seawater to reach the warmer, mineral-rich pools. It’s not a spa in the traditional sense, no tiled baths or champagne flutes, but it’s an authentic reminder that the volcano is alive, simmering just beneath the surface.

8. The Caldera is Among the Largest in the World

Santorini’s caldera measures about 12 kilometers across, making it one of the largest and most dramatic in the world. When cruise ships anchor inside, they look like toys dwarfed by the towering cliffs that rise up to 400 meters.

The sheer scale is difficult to comprehend until you stand at the edge in Fira or Oia, looking down at the sea-filled crater. Unlike other volcanoes where you peer into a crater from above, in Santorini you live inside it. Entire villages are built along its rim, and thousands of people watch sunsets each evening without realizing they are perched on the edge of a volcanic cauldron.

9. The Volcano Shaped Santorini’s Architecture and Tourism

Santorini’s iconic look, cave houses carved into cliffs, whitewashed walls, narrow alleys, exists because of the volcano. The porous volcanic rock made it easy to carve out homes, keeping them cool in summer and warm in winter. The abundance of pumice also allowed locals to build structures that were lightweight yet strong.

Tourism, too, is built on the caldera. The cliffs provide the dramatic views that have made Santorini one of the most photographed places in the world. The volcano is not just part of the past, it is part of the island’s ongoing identity, shaping its economy and reputation as a global destination.

10. Santorini Could Erupt Again

This is the question people always ask: will Santorini erupt again? The answer is yes, eventually. All volcanoes that are still active will erupt at some point. But scientists believe the next eruption will likely be small, similar to the 1950s, and confined to Nea Kameni.

That said, the volcano is carefully monitored, and any signs of serious activity would be detected early. Santorini today is considered safe, and millions of visitors experience its beauty every year without issue. In fact, standing at the edge of the caldera, knowing the earth is alive beneath you, makes the island feel even more extraordinary.

Editor’s Note

I first visited the volcano in January, during the winter of 2020, and it was an unreal experience seeing Santorini from Nea Kameni. It’s something you just can’t explain, standing there and watching sulfur rise from the volcano. Swimming in the thermal springs afterward was unforgettable.

If you’ve ever wondered what Santorini is like in the winter, I shot a film during that trip, showcasing an empty island with nothing but nature sounds and views. You can watch it here: NakedSantorini — a 3-part series.

Closing Thoughts

Santorini’s volcano and caldera are not just geological features, they are the heart of the island’s identity. They shaped its history, destroyed civilizations, created myths, fueled its agriculture, and built its tourism industry. The sunsets, the wines, the architecture, and even the cliffside towns all owe their existence to the restless giant beneath the sea.

When you sip wine in Oia, swim in the hot springs, or sail past Nea Kameni, you are part of a story that began thousands of years ago and is still unfolding. Santorini is more than beautiful, it is alive. And that is what makes it one of the most fascinating places on earth.

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