The picturesque gorge of the Erma River (Trun Gorge) is located about 3 km from the town of Trun and represents one of the attractive natural landmarks in this part of the country. The gorge has a length of about 100 meters and a width in the narrowest part about 5 meters. On both sides of the river stand vertical rocks with a height of about 150-200 m.
For the curious tourists and nature lovers, there is a special eco-path starting from the southern end of the canyon. The route is 13 km long and passes through wooden bridges over the Erma River, continues through a tunnel cut into the rock, and behind it is a 35-meter-long wooden bridge, after which the ascent of the western rock of the gorge begins. The most interesting and attractive sites along the route of the eco-trail are the two gorges – the Erma River and the Yablanishka River.
The view revealed by the eco-path stops breathing with its impressive rock formations in river gorges, sparkling waterfalls and water thresholds.
Erma’s gorge is the result of the millennial erosive action of the river, which has cut a deep lime into the limestone. More than a century ago, visiting the gorge, the great Bulgarian writer Aleko Konstantinov exclaimed, “What, Switzerland?”.
Erma’s gorge is declared a natural landmark. But here is also the living nature. Only a few square kilometres meet dozens of tree, shrub and grass species. Some of them are exceptionally beautiful, such as the lilac in May or the sumac in September and October, and especially the rare rarely occurring only on the Balkan peninsula, the Iris reichenbachii, which can be seen in June.
The bird kingdom also impresses with its wealth – there are interesting species such as White Stork (Ciconia ciconia), Pernis apivorus, Circus pygargus and others. Lutra lutra, Rhinolophus hipposideros, Rhinolophus ferrumequinum, European wolf (Canis lupus), Lynx lynx, etc. are found here. Amphibians are represented by Triturus karelinii, Bombina variegata and others.