Santorini is the remnant of a volcanic caldera located in the Mediterranean.
The Aegean Sea ( [ ᵻˈdʒiːən ] Αιγαίο Πέλαγος [ eˈʝeo ˈpelaɣos ] ; Ege Denizi [ eɟe denizi ] ) is an elongated embayment of the Mediterranean Sea located between the Greek and Anatolian peninsulas , i.e. , between the mainlands of Greece and Turkey . Santorini . It is the largest island of a small , circular archipelago which bears the same name and is the remnant of a volcanic caldera . Santorini is essentially what remains after an enormous volcanic eruption that destroyed the earliest settlements on a formerly single island , and created the current geological caldera . The main island slopes downward to the Aegean Sea .