When in the region of Drama, it is worth visiting the Aggitis cave (also called Maaras Cave). It is located NE of the capital, close to Prosotsani, on the south foot of Falakro mountain. There the freezing Aggitis river springs from the depths of the mountain. It is the largest in length and volume cave in Greece and it is a river cave, the only one existing in Greece!
The cave is an elongated natural pipe. It’s almost the only draining path for the waters collected in the closed basin of Kato Nevrokopi. A great chamber was discovered reaching 500 m length. Its roof is full of stalactites, some of which have a diameter of 2m. and touch the surface of the water. Their colors are amazing, due to the existence of minerals such as manganese, iron, copper etc.
Nowadays, 8.5 km have been explored and only 2.5 are accessible to visitors. You can enter the cave from the artificial entrance that has been opened and walk for 500 m. Stalactites of various forms, sizes and colors decorate the cave. As for stalagmites, their number is very limited because of the continuous flow of the river… http://www.visitgreece.gr/en/nature/caves/aggitis_cave