The sea level surrounding the Volcano is 390 metres deep. Palea and Nea Kameni are connected with a portion of the volcano peaking to the surface at 100-150 metres. There is an underwater flat-surfaced dome with a diameter of 200 m. and 40-50 m. depth with small peaks 33m. under the sea level. There was another underwater dome 188m. deep located between Palea Kameni and Aspronisi. Prior to the eruption of the volcano 1925-1926, there was a third underwater dome under Palaia Kameni named Bangos and served as an anchor of ships but unfortunately it was destroyed by the lava and Bangos no longer exists. H. Reck in his book ‘Santorini 1936’ mentions that in the prehistoric era there was a complex of islands close to Thira that were connecting mainland Greece with Asia (Turkey) and Crete. Philippson, a geographer/geologist named them ‘Aigida’. Aigida had many mountains and lakes, amongst them, there was a mountain range named East-Aegean which includes the church of Prophet Elias, and branched out to Platanimou and ‘Mesa Vounou’ in Exo Gonia. Years later, different sectors of Aigida sunk into the sea and what is left is how we know it today the Aegean islands.
In the middle of 2000 years BC and after a long period of tranquillity, there was a destructive phenomenon in the north sector of the island that blasted a thick layer of pumice, which led to the present shape of the complex islands of Thira, Thirasia and Aspronisi.
After the creation of the Caldera, the lava poured into the bottom of the sea, which formed small islands like Palaia Kameni, in 1570 AD Mikra Kameni was formed and in 1707-1709 Nea Kameni was created.
In the north-east of the island of Thira, in 1650 AD, The volcanic eruption formed the reef Kouloubos, which is an underwater dome with a peak at a depth of 18m. In 1929 there was a small explosion in the lava stream that lasted for two months. As a results there was another dome created called ‘Nautilos’
The by-products of the volcanic activities benefited the soil of Santorini in a way that boosted farming and agriculture. As a result, the wine of Santorini is created with grapes that are only watered by rain. Similarly potatoes, tomatoes, barley, wheat, cucumbers and other vegetables.