The postcard-blue bay that cruise ships sail into at Santorini is not a harbor — it's a crater. The cliffs the whitewashed villages cling to are the inner wall of a caldera, blasted open around 1600 BCE by one of the largest eruptions of the last 5,000 years. Our Smithsonian GVP data records that Minoan eruption at VEI 7 — one of only seven VEI-7 eruptions in our entire Holocene database. And the volcano isn't finished: it last erupted in 1950, and the black islets in the middle of the bay are the active cone still growing back inside the crater.
By VolcanoDB Research Team. Data: Smithsonian Global Volcanism Program (Santorini, #212040); Institute for the Study and Monitoring of the Santorini Volcano (ISMOSAV).
Minoan Eruption
VEI 7
Recorded Eruptions
11
Last Eruption
1950
Caldera Rim
~300m
The Minoan Eruption: a VEI-7 That Reshaped the Aegean
Around 1600 BCE, in the Late Bronze Age, Santorini — then a single larger island the Greeks called Thera — tore itself apart. Magma met seawater, drove a towering Plinian eruption column, and then the emptied chamber gave way: the middle of the island foundered into the sea, leaving the roughly 12-by-7-kilometer flooded caldera you see today. Our GVP database records this Minoan eruption at VEI 7, the “super-colossal” tier of the Volcanic Explosivity Index.
Nobody has pinned the exact size, because most of the eruption fell into the sea rather than onto land. Published estimates for the erupted volume range from roughly 13 to 86 cubic kilometers of dense-rock equivalent; a 2018 reconstruction that combined onshore deposits with marine and geophysical data landed near 34 km³ DRE (Karstens et al., Scientific Reports). Even the low end puts the Minoan eruption among the largest of the last 5,000 years — far bigger than Krakatoa in 1883.
The human story is what makes it famous. Ash and pumice buried the Minoan port town of Akrotiri— frescoed, multi-storey, with drainage and paved streets — so completely that it's often called the Minoan Pompeii. The eruption, and the tsunamis it likely sent across the Aegean, are widely linked to the decline of Minoan Crete, and the drowned-island imagery has fueled the Atlantis legend ever since Plato. Those connections are genuinely argued by scholars but remain debated — treat the Atlantis tie as a story the eruption inspired, not a proven fact.
The exclusive club: every VEI-7 eruption in our Holocene database
Across all 11,000+ eruption records in our database, only seven reached VEI 7 in the Holocene — and nonereached VEI 8. Santorini's Minoan eruption is one of the seven, and the second-most-recent of them.
Source: VolcanoDB analysis of Smithsonian GVP eruption records. See the full ranking on our supervolcanoes page.
It's Not Extinct — Santorini Is Still Active
This is the part the travel blogs skip. Santorini is an active volcano, and our database proves it: 11 recorded eruptions, the most recent in 1950. After the Minoan catastrophe the system started rebuilding almost immediately — the first post-Minoan eruption, in 197 BCE, pushed up Palea Kameni(“old burnt island”), and a long series of eruptions from 1570 CE onward built its younger neighbor, Nea Kameni(“new burnt island”). These two dark, barren islets in the center of the bright-blue bay are the live volcano — the visible tip of the magma system that's still there.
The volcano last stirred in 2011–2012, when monitoring picked up ground inflation and a swarm of small earthquakes beneath the caldera — a reminder that magma is still moving down there — before the unrest quieted without an eruption. Santorini is watched continuously by ISMOSAV and international research teams; you can also see its live-feed status on our erupting-now dashboard and browse the full data record on the Santorini database page.
Period
VEI
Type
Notes
1950 CE
2
Explosive + lava dome
The most recent eruption: a small dome and lava flow on Nea Kameni with explosive activity. This is why the volcano is classed as active, not extinct.
1925–1928
2
Dome-building
A run of 20th-century eruptions (1925, 1928, 1939, 1950) that enlarged Nea Kameni, the young islet at the center of the caldera.
1866–1870
2
Dome-building
The Georgios dome grew during a multi-year eruption watched — and painted — by early volcanologists; among the best-documented eruptions of its era.
726 CE
4
Explosive
The largest post-Minoan eruption on record — pumice was reported falling as far as the coasts of Asia Minor. The only VEI-4 in Santorini's historical record.
197 BCE
3
Explosive + dome
The first eruption after the Minoan catastrophe, and the birth of Palea Kameni — the older of the two islands inside the flooded caldera.
~1600 BCE
7
Plinian / caldera collapse
The Minoan eruption. A super-colossal blast that emptied the magma chamber, collapsed the center of the island into the sea, and buried the Bronze-Age town of Akrotiri.
The Santorini Volcano Boat Tour: What You Actually Do
The single best way to understand Santorini's geology is to sail out to the middle of it. The standard volcano boat tour leaves from the old port below Fira (reached by cable car, donkey, or a steep walk) or from the main ferry port at Athinios, and heads for Nea Kameni. You land on the black volcanic rock and walk a marked trail up to the rim of the young cone — around a 20–30 minute climb over loose scoria — passing fumaroles where you can smell sulphur and feel the warm ground. This is as close as most people ever stand to an active crater.
Most tours then anchor off Palea Kameni so you can swim from the boat into the shallow hot springs — a patch of iron-rich, rust-colored water noticeably warmer than the Aegean around it (the color stains light swimwear, so wear something dark). Longer trips add the quiet island of Thirassia — a surviving fragment of the pre-Minoan caldera rim — and finish with the famous Oia sunsetfrom the water. Bring closed-toe shoes for the sharp lava, water, and sun protection; there's no shade on Nea Kameni.
Book a Nea Kameni volcano & hot springs boat tour
Compare Santorini volcano boat tours — Nea Kameni crater walk, Palea Kameni hot springs, Thirassia, and sunset cruises — from local operators sailing out of Fira and Athinios.
Compare guided hikes, crater walks, and day trips near Santorini from local operators in Greece.
VolcanoDB may earn a commission on bookings made through these links, at no extra cost to you.
The Caldera You Photograph Was Built in Four Collapses
The colored bands in the caldera cliffs — red, black, pink, white — aren't decoration; they're a stacked record of eruptions, and the caldera itself isn't the product of a single event. According to the geologic record in our database, Santorini has collapsed at least four times. The oldest caldera formed about 180,000 years ago, a second (the Skaros caldera) about 70,000 years ago, a third (Cape Riva) about 21,000 years ago, and the youngest — the one cruise ships anchor in — during the Minoan eruption about 3,600 years ago.
Between collapses the volcano rebuilds, which is exactly what Nea Kameni and Palea Kameni are doing now: overlapping shield and dome growth inside the flooded crater. It's a live example of how a caldera volcano works over deep time, and why Santorini is one of the most-studied volcanic islands on Earth. For the geologically curious, that's the real souvenir: you don't just see the view — you understand you're standing inside the crater of a supervolcano-scale eruption.
Frequently Asked Questions
Is Santorini a volcano?
Yes. The whole island group is a volcano. The flooded, cliff-ringed bay that cruise ships anchor in — the caldera — is a crater left when the center of the island collapsed during the Minoan eruption around 1600 BCE. The two small dark islands in the middle of the bay, Nea Kameni and Palea Kameni, are the young active cone that has grown back since. Santorini sits on the Hellenic Volcanic Arc, where the African plate dives beneath the Aegean.
Is the Santorini volcano still active?
Yes, it is active, not extinct. Our Smithsonian GVP database records 11 eruptions at Santorini, the most recent in 1950 CE. That eruption built a small lava dome and flow on Nea Kameni. Since then the volcano has been quiet apart from a period of unrest in 2011–2012, when instruments recorded ground inflation and increased seismicity that faded without an eruption. It is monitored continuously by the Institute for the Study and Monitoring of the Santorini Volcano (ISMOSAV).
When did the Santorini volcano last erupt?
The last eruption was in 1950 CE — a small VEI-2 event on Nea Kameni. Before that, Santorini erupted repeatedly in the 1800s and 1900s (1866, 1925, 1928, 1939), each time enlarging the central islands. Its most violent historical eruption was in 726 CE (VEI 4). The famous Minoan eruption — the one that made the caldera — was around 1600 BCE.
How big was the Minoan eruption of Santorini?
It was a VEI-7 eruption, the second-highest rating on the Volcanic Explosivity Index — one of only seven VEI-7 eruptions in our entire 11,000-record Holocene database. Published volume estimates vary widely because most of the erupted material fell into the sea; figures range from roughly 13 to 86 km³ of dense-rock equivalent, with a 2018 reconstruction putting it near 34 km³ DRE. Either way it ranks among the largest eruptions of the last 5,000 years.
Can you visit the Santorini volcano?
Yes — this is the classic Santorini excursion. Boats leave the old port below Fira (and from Athinios) for Nea Kameni, where you walk up to the rim of the active cone past steaming fumaroles, then usually stop at Palea Kameni to swim in the warm, iron-stained sulphur springs. Many trips combine the volcano with the island of Thirassia and an Oia sunset. Book a Nea Kameni volcano boat tour through the module above.