Ainos mountain is the highest mountain on Kefalonia and in all the Ionian islands, at an elevation of 1628m at its summit (around one mile above sea level). In comparative terms, it's higher than Ben Nevis in the UK (1344m) and just slightly higher than the city of Denver, Colorado, USA (1609m).
The views from the summit are worth the trek up. On a clear day the whole of Kefalonia, most of Ithaka and parts of Zakynthos, Meganissi and Levkas are visible, also Kyllini and the mainland coast.