The riνer Angitis is a main element in the hydrographic network of the lowlands of Drama. It starts at the Maara springs, crosses the western side of the low-lands and having collected its waters at Philippi pours into the Strymon river. The mean annual amount of water supplied by the springs has been calculated at 3 cubic metres per second and the mean annual amount of water supplied by the Angitis, having collected all its waters, is 8 cubic metres per second.
The Maara springs at an altitude of 123m are the outlet of an underground river which crosses the Maara cave. The cave is a pipeline conduit (karst phenomenon) which is directly connected with the sink-holes of Ochyro οn the Kato Nevrokopi plateau at an altitude of 535m.
The underwater river is fed by waters from streams of the Kato Nevrokopi plateau which drain through the Ochyro sinkholes and are channelled through the underground (karst) system.
Just in front of the outlet of the water there is a waterwheel which has been there since the Turkish occupation which was used to raise water from the river and then irrigate the surrounding villages.
Today the cave has been explored for 8.5 km of its length and is accessible for 2.5 km, of which the first 500m are open to the public for visits while it is estimated that the real length of the cave is 12 km. Inside the cave the temperature of the water is 13^o C and the air temperature is 17^o C. Along the length of the cave there are flat area and chambers up to 25m in width alternating with narrower areas up to 1m wide. Α characteristic feature of the cave is the underground river and the stalactites in a variety of colours, shapes and sizes (there are hardly any stalagmites in the cave).

See also the following photos: