The island of Cephalonia or Kefalonia is about 781 square km (300 square mi), with a population density of 55 people per square km (140 per square mi).
The town of Argostoli has one-third of the island’s inhabitants. Lixouri is the second major settlement, and the two town’s together account for almost two-thirds of the prefecture’s population.
Cephalonia lies in the heart of an earthquake zone, and dozens of minor, unrecorded tremors occur each year. In 1953, a massive earthquake destroyed almost all of the settlements on the island, leaving only Fiskardo in the north untouched.
Important natural features include Melissani Lake, the Drogarati caves, and the Koutavos Lagoon in Argostoli.
The island has a rich biodiversity, with a substantial number of endemic and rare species. Some areas have been declared a site in the European Union’s Natura 2000 network.