Tran gorge, Natural ravine and scenic viewpoint near Tran, Bulgaria.

Tran gorge is a natural ravine carved by the Erma River through limestone near the town of Tran. The formation features steep rock walls that run for several kilometers along the river valley.

The gorge was declared a natural landmark in 1961 under the name Gorge of the River Erma to protect its rock formations. A 200 m tunnel beneath Zhilav Kamak was excavated in the early 20th century for a railway between Tran and Tsaribrod, when the latter belonged to Bulgaria. The unfinished tunnel from the Second World War, dug by Germans, remains as another trace of wartime engineering.

The gorge is linked to a local legend: a wealthy girl and a poor youth, cursed by a mother's oath, were turned into the two rocks on either side of the Erma, always near but never together, and the river is fed by their tears. The writer Aleko Konstantinov described the gorge in his travelogue "What? Switzerland?", and the painter Nikola Petrov depicted its surroundings in his 1913 canvas Erma River near Tran.

A marked hiking trail starts from a parking area with resting spots and bathroom facilities for visitors. The path is easiest to walk during dry weather when the ground is most stable underfoot.

The two crags above the narrowest point are named Tsarkvishteto (the Church) and Zhilav Kamak (the Hardy Rock); the latter is pierced by a 200 m tunnel dug in the early 20th century for a planned Tran–Tsaribrod railway. Alpine climbing routes now run on both rocks.