The cave of Melissani is located near Karavomilos on the island of Kefalonia. It is a lacustrine cave of unique beauty and fully developed cave, which is 3.5 km long, 40m wide and 36m high. Melissani cave constitutes a unique geological phenomenon. It was created by a mechanical and chemical process called karstikopoiisi (dissolution of rocks) during which water enters the calcareous rocks, erodes them and creates hollows.

The Aggitis River Cave, also known as the Maara Cave, is a stunning natural attraction located near the village of Aggitis in the Drama region of northern Greece. It is one of the longest river caves in the world and a significant geological and tourist site. The cave is approximately 21 kilometers long, though only a portion of it (about 500 meters) is accessible to visitors.

Greece is a country in Southeast Europe. It is situated on the southern tip of the Balkans, and is located at the crossroads of Europe, Asia, and Africa. The country consists of nine traditional geographic regions, and has a population of approximately 10.7 million. Athens is the nation's capital and largest city, followed by Thessaloniki.