Campi Flegrei Mar Sicilia
Campi Flegrei del Mar di Sicilia is a field of submarine volcanoes located south-west of Sicily. It includes the vent of Ferdinandea, otherwise known as Graham Island, which erupted and emerged above sea level in 1831, and encompasses a larger volcano known as Empedocles.
Source: Wikipedia — Campi Flegrei Mar Sicilia (CC BY-SA 4.0)