The Trigrad Gorge is the most dramatic landscape feature in the Rhodope Mountains: a narrow slot canyon carved by the Trigrad River through pale limestone cliffs that rise 300 metres above the narrow valley floor. The road through the gorge is barely wide enough for two cars passing; the walls close in to near-vertical above, and in the depths the river disappears entirely into the rock.
The gorge's centrepiece is the Devil's Throat Cave at its southern end — a massive cave system through which the Trigrad River plunges 42 metres underground, disappearing into a chasm visible from a viewing platform before re-emerging 2 kilometres away through a different exit. The cave is open to visitors along a concrete walkway; the roar of the underground river, the spray, and the darkness make it one of the most viscerally impressive show caves in Bulgaria. From Trigrad village, the walk into the gorge takes about an hour; the drive from Smolyan takes 45 minutes on winding mountain roads.