Which Greek peninsula includes the monastic region of Mount Athos?

The Greek peninsula that includes the monastic region of Mount Athos is Chalkidiki.

Chalkidiki, also spelled Halkidiki or Chalcidice, is a large peninsula in northern Greece’s Central Macedonia region. It is famous for its three long projections into the northwestern Aegean Sea: Kassandra, Sithonia and the Mount Athos peninsula.

Mount Athos forms the easternmost of these three ‘fingers’. It is a self-governing monastic community within Greece, home to Orthodox monasteries and restricted access. Mount Athos itself rises to 2,033 metres, making it the highest point on the Chalkidiki peninsula.

A frequent misunderstanding is to treat Mount Athos as a separate Greek peninsula. Geographically it is part of Chalkidiki, although administratively the autonomous Mount Athos region is separate from the Chalkidiki regional unit. Pelion, Attica and Mani are other Greek peninsulas but do not contain Mount Athos.