The mountain range of Ordymnos dominates the western peninsula of Lesvos, with its highest peak reaching 634 meters, the volcanic dome of the Ypsilos Monastery, which with its conical shape is one of the most characteristic volcanic dome of Lesvos.
The volcanic dome was formed in the last phase of volcanic activity, 16.5 million years ago, and is the largest of a series of volcanic domes arranged along a large tectonic rupture running from north to south.
Its creation is associated with a rise of magma that moved at low speed, penetrated the earlier metamorphic rocks of the bedrock, clouded the layers of pyroclastic formations that covered the area and created a giant dome without causing a volcanic eruption. The magma cooled and solidified at a relatively shallow depth and the erosion of the pyroclastic rocks that surrounded it revealed the more resistant volcanic rocks, which form the present landscape of the region.
On the northern side of the hill, impressive columnar lava forms appear, which were created due to the rapid cooling of the igneous material.
At the top of the volcanic dome, in the place of an older fort and Byzantine friary, is built the Monastery of Agios Ioannis the Theologian. Tradition places the foundation of the monastery in Byzantine times, before 800 AD. and is known as the High Monastery.