The island you see today — a crescent of cliffs wrapped around a flooded volcanic caldera — is the direct result of a catastrophic eruption sometime in the second millennium BCE, among the largest volcanic events of the last several thousand years. Before it, the island was a roughly circular landmass; the eruption blew out its centre, and the sea rushed in to fill the collapsed caldera left behind.
A Bronze-Age catastrophe
At the time, a sophisticated Bronze-Age settlement stood at what's now Akrotiri, part of the wider Minoan trading world centred on Crete. The eruption buried the town under metres of ash, preserving it in remarkable detail — see our Akrotiri guide — while the wider event is thought to have sent tsunamis across the Aegean and possibly contributed to the decline of Minoan civilisation on Crete itself, though historians still debate exactly how much impact it had.
Shaping the island you visit today
Nearly everything distinctive about modern Santorini traces back to that eruption: the caldera cliffs that give every clifftop hotel its view, the black, red and white volcanic beaches, the ash-and-pumice soil that makes the island's wine and tomatoes what they are, and the smaller volcanic islets — Nea Kameni and Palea Kameni — still visible in the middle of the caldera, remnants of later, smaller eruptions.
Visiting the volcano today
Boat tours from the old port or Vlychada marina run out to Nea Kameni, where a short hike crosses the still-warm volcanic crater, often combined with a stop at the hot springs near Palea Kameni for a swim in mineral-tinted water.
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