The modern Greek island of Santorini is a popular holiday destination, but the island holds a dark secret. In 1613 BC, give or take a couple of decades (scholars lock horns over the dates), the circular Aegean island of Thera (now Santorini) was almost obliterated from the earth. With the force of many Krakatoas, the volcano which lay beneath it blew its top in an explosion which threw most of the island into the sky and scattered it over and beyond the sea. The lava thrown out of the volcano with such force fell back already aerated, as a thick layer of light pumice which lies over the remains of the island to this day and can be seen in the curved cliffs like a thick pastry crust on a pie bitten by a giant. The town of Akrotiri, once a Minoan settlement, lies excavated from the ash, a Theran Pompeii.
The collapse of the sea floor beneath Thera produced a tsunami that swept across the Aegean. The north coast of Crete was devastated, with coastal towns like Palaikastro completely inundated, the palace at Amnisos damaged and pumice falling on Mallia. Molten lava thrown out of the crater flowed out across the sea, cooled and sank, leaving over five hundred square miles of the sea floor around Santorini covered in a thick layer of volcanic rock.
The Mediterranean is in constant geological turmoil. Think of Etna and Vesuvius, the earthquakes which are slowly unzipping the crust of northern Turkey towards Istanbul. There are seething thermal vents on the seafloor a few miles from Santorini now, and the Aegean itself will disappear one day, crushed between Africa and Europe in the relentless dance of tectonic plates. This was the largest volcanic eruption in human history until Tambora exploded in Indonesia in 1815, and its after-effects are still not yet understood.
As for the date of 1613 BC: two olive branches, the remnants of a walled olive-grove alive on Thera when the eruption blasted away the land next to it, were found intact under the pumice by archaeologists and radiocarbon-dated. Olive trees are survivors.
Memories of this ancient disaster may have given rise to the later myths of Atlantis, the kingdom which sank beneath the sea. Plato, the ancient Greek philosopher, wrote of the story of Atlantis. This story filtered through in later years to Arab geographers, which is how medieval European writers learned of it.
Also in the middle ages, the town of Old Winchelsea in East Sussex was swept away by massive flooding in a storm in 1287.