Tranquil Aegean waters fill the caldera, or basinlike depression, created by the collapse of the volcano at Thera following its huge explosion 3,500 years ago. Jagged rocks in the foreground mark the top of one wall of the caldera. The two small islands in the distance, Palea Kameni and Nea Kameni, emerged in the center of the crater when eruptions forced lava above the surface of the water. Thera’s partially submerged volcano, though dormant, is not extinguished; smoke can be seen on Nea Kameni even today.

The great eruption at Thera more than three millennia ago spewed smoke and debris 20 miles in the air, sending dust particles hundreds of miles away. The blast not only ended Thera’s impressive culture—exemplified by extraordinary wall paintings, a selection of which are shown on the pages that follow—and its seafaring commerce, but it has also been linked by some scholars to the sudden eclipse of Minoan civilization, to the Israelite Exodus from Egypt and even to the storied disappearance of Atlantis.