Therasia, also known as Thirasía , is an island in the volcanic island group of Santorini in the Greek Cyclades. It lies north-west of Nea Kameni, a small island formed in recent centuries by volcanic activity and thus marking the centre of the island group. Therasia is the second largest island of the group, the largest by far being Thera.

Therasia, also known as Thirasía , is an island in the volcanic island group of Santorini in the Greek Cyclades. It lies north-west of Nea Kameni, a small island formed in recent centuries by volcanic activity and thus marking the centre of the island group. Therasia is the second largest island of the group, the largest by far being Thera.