With its romantic sunsets, dazzling ocean views, and whitewashed buildings clinging to rocky clifftops, the Greek island of Santorini (aka Thera or Thira) is the very picture of an idyll in the Aegean. But this tranquil scene belies the island"s explosive geologic history, for this is the site of one of the largest volcanic eruptions in recorded history. The Minoan eruption, about 3,600 years ago, caused the center of the Thera volcano to collapse into the ocean, leaving Santorini a jagged, crescent-shaped moon atop the sea.