Kefalonia’s beauty not only lies on its surface. One of its most interesting attractions, the Drogarati Cave, lies underground. According to speleologists, the cave is over 150 million years old. Multi-colored stalactites and stalagmites fill the cavern. The cave has a second part which is accessible to tourists. This portion holds the Royal Balcony that has translucent stalagmites. From this balcony can be seen the Chamber of Exaltation, an area which can accommodate about 500 people and has an excellent acoustic.

The island is mountainous – more mountainous than any other island in Greece – with its tallest peak, Mount Ainos reaching 1626 meters. The mountain is home to a rare species of fir, the Greek Fir (Abies cephalonica), its name indicating that it was discovered in Kefalonia. The Greek Fir is a large evergreen forming a dense forest in the mountains of Greece. The ancient Greeks used its timber to build ships. At present, however, Greef Fir-cutting has been greatly reduced ever since Mount Ainos has been declared a National Park.

Amid Kefalonia’s gorgeous landscape are numerous churches and monasteries – so numerous in fact, that specialists have dubbed the island a "vast ecclesiastical museum". The Monastery of Saint Gerasimos is among the famed Kefalonia monasteries. It is considered to be the island’s most sacred site, where pilgrims from all over Greece flock to visit the saint’s relics. One of the most interesting churches is the Church of the Virgin Mary Markopoulo because of the small harmless snakes that come out and appear all over the church every August just before the festival of Panaghia. After the snakes have climbed all over the icons, they disappear and exactly on the day of the festival. The Monastery of Atros is impressive not only because of its structure but also because of its history. The monastery was devastated by earthquakes and fires 17 times and yet the monks rebuilt it again every time. It is the oldest monastery in Kefalonia and was built during the Byzantine period.