Devils Throat Cave

Devil's Throat Cave, or Dyavolsko Garlo, is located in the western Rhodopes close to the village of Gyovren in Bulgaria, near its border with Greece. A popular tourist attraction, Devil's Throat branches from Trigrad Gorge.

The cave’s entrance resembles a devil’s head, and down its throat rushes a massive waterfall that from ancient times has given birth to numerous legends.

It is a fact that nothing carried by the river into The Devil’s Throat Cave emerges back from it. Many attempts have been made to track pieces of wood and other material through the cave, but they all vanish without a trace in the underground river.

Source: Wikipedia