Volcanism along the South Aegean volcanic arc began about 4.7 Ma and has lasted until the present day, with eruptions at Methana, Milos, Santorini, Kolumbo and Nisyros volcanoes in historical times. These volcanoes can be grouped into five volcanic fields: three western fields of small, mostly monogenetic edifices, and two central/eastern fields with composite cones and calderas that have produced large explosive eruptions. Crustal tectonics exerts a strong control over the locations of edifices and vents at all five volcanic fields. Tephra and cryptotephra layers in deep-marine sediments preserve a continuous record of arc volcanism in the Aegean as far back as 200,000 years. Hazards from the volcanoes include high ash plumes, pyroclastic flows and tsunamis. Monitoring networks should be improved and expanded.