The “Dyavolsko gurlo” cave (Devil's Throat – Bul.)  was formed by a landslide. It can be visited after a 35 km., drive from the "Sinanovi" guest house and is located at no more than a kilometer and a half from the Trigrad village in the “Trigrad Gorge” of the Rhodope mountains. Its main inside consists of a large hall which hosts the highest underground waterfall on the Balkans. The name of the cave is derived from the shape of its former entrance (nowdays its exit), which resembles the shape of a devil's head. The cave was formed from the erosion of river waters falling underground from a height of 42 meters thus forming a huge hall called the “Roaring hall”. It is 110 meters long and 40 meters wide and its roof stands at a height of 35 meters. After the entrance hall of the “Devetashka” cave this is the second largest cavity in all of the numerous Bulgarian caves - it can easily host Sofia’s central "St. Alexander Nevsky" cathedral. The cave can be accessed through an artificial gallery with a length of 150 meters which reaches the base of the watercourse. From here 301 stairs will take the visitor past the underground waterfall and through the old entrance back to ground surface. About 400 meters from the entrance of the “Dyavolsko gurlo” the waters of the underground river are lost in a siphon gallery. The length of this siphon is more than 150 meters after which, and along  a 60-meter gallery, the underground river leaves the cave and flows out on the surface of the ground.