The Santorini Greece Volcano: Nea Kameni and Palea Kameni
Two dark islets sit in the middle of the caldera, and they are the youngest land in the Aegean. One of them you walk up. The other you swim beside. Neither has a road, a shop or a scrap of shade.
Where the volcano actually is
The caldera measures about 12 by 7 kilometres, with cliffs some 300 metres high on three sides and water 385 metres deep in the middle of it. The rim you stand on is the rest of the mountain. The two islets in the centre are what has grown back since.
Santorini is the most active volcanic centre in the South Aegean Volcanic Arc and one of the world's sixteen Decade Volcanoes, the group singled out for close study because of what they have done and who lives near them.
Nea Kameni, the one you walk on
The larger and younger islet is a national geological park. Boats moor at a landing on its shore and a gravel path climbs to the crater rim, past vents that still smell of sulphur. It is bare, black and completely exposed.
It last erupted in January and February 1950. That is recent enough to be within living memory on the island, and it is the reason the ground has no soil on it.
Palea Kameni, and the water beside it
The older islet is smaller and you do not land on it. What you do is swim into the shallow bay on its edge, where iron-rich water seeps out warmer than the sea and stains everything around it rust-orange.
Boats moor about fifty metres out because they cannot get closer, so the hot springs involve a swim in open water before you reach the warm part. It is a few degrees above the sea rather than hot, and the iron marks light fabric for good.
The EUR 5 nobody tells you about
Landing on Nea Kameni costs EUR 5 a head, collected in cash by the park at the landing itself. It is almost never inside a boat fare, and there is no card machine on the rock. Carry coins or a small note.
One of the boat trips here names that fee in its own exclusions, which is a useful signal: an operator who prints it is an operator who expects you to arrive with it.
What the walk is actually like
It is a steady uphill of loose volcanic gravel with no steps and no shade, and it takes most people twenty to thirty minutes each way. Boats usually allow about an hour ashore, which is enough to reach the rim, walk part of it and get back without hurrying.
Wear closed shoes. Listings say comfortable shoes and reviewers keep pointing out that on scree that is not the same instruction. Take water; there is none up there.
The eruption record
| Roughly when | What happened |
|---|---|
| Late Bronze Age | The eruption that emptied the chamber and dropped the rim, burying the town at Akrotiri |
| 197 BC onward | The islets begin to appear in the caldera |
| 1707 to 1711 | A long eruption enlarges Nea Kameni |
| 1866 to 1870 | One of the best-documented historical eruptions here |
| 1925 to 1928 | Further growth of the islet |
| January to February 1950 | The most recent eruption |
The date of the big one, and why it is disputed
The Late Bronze Age eruption reached VEI 7 and threw out something like 28 to 41 cubic kilometres of rock. When it happened is genuinely unsettled: archaeological chronology says around 1500 BC, radiocarbon says roughly 1645 to 1600 BC, and tree rings say 1628 BC.
The town it buried is the subject of the Akrotiri page, and the same disagreement runs through both.
Thirasia, the piece that stayed
The western fragment of the old rim is a separate inhabited island of a few hundred people, reached by boat and almost untouched by the day-trip traffic. Two of the boat trips here stop there, one for half an hour and one for two hours.
Getting there without a tour
You can. Scheduled boats run from the Old Port below Fira to the islets and back, you pay the EUR 5 at the landing, and you are on your own timetable. What a guided cruise adds is the hot springs stop, a meal, the swim stops the scheduled boats skip, and somebody who knows which side of the crater to walk.
The arithmetic is set out in full in our guide to doing it independently, including when the answer is that you should.
Which trips land, and which sail past
Read the itinerary rather than the title. Of the boat days here, one proves a landing by excluding the park fee, two name the hot springs as a stop, and three carry a timed stop simply called the volcano without settling whether you go ashore.
| Trip | What its own itinerary says | Hours |
|---|---|---|
| 1-Day Boat Trip: Santorini Volcano, Thirassia & Oia Sunset | Lands on the crater; excludes the EUR 5 fee | 14 |
| Santorini Classic Catamaran Cruise with BBQ, Drinks and Transfers | Hot springs swim off Palea Kameni | 5 |
| Santorini Luxury Catamaran Sunset Cruise with BBQ, Drink and Transfer | Hot springs swim, then Red and White beaches | 5 |
| Half-Day Exclusive Catamaran Cruise in Santorini with Meal and Open Bar | A timed stop at the volcano | 5 |
| Luxury Santorini Catamaran Cruise: Lunch, BBQ, Drinks, Transfers | A timed stop at the volcano, plus Thirasia | 5 |
Book the boat, not the walk
There is no way onto the crater except by sea, so the trip you book is the trip that decides whether you get there at all.
Where these figures come from
- The EUR 5 national park fee: named in the exclusions of the volcano boat trip listed here, and reported the same way by independent visitor guides.
- Caldera dimensions, depth, the eruption record and the 1950 date: the standard reference literature on the Santorini caldera and Nea Kameni, read 5 September 2026.
- Landing and stop times: each operator's own published itinerary.
Fares and opening hours change. Check before you travel.
What the wind does to all of this is on the weather page, and the boat days themselves are on the Santorini Greece Tours home page.