Located about 7km away from Terni, there is the Marmore waterfall, whose name derives from the calcium carbonate salts present on the rocks which are similar to white marble.
The waterfall, one of the largest in Europe, is formed by the Velino river, near the hamlet of Marmore, drains from Lake Piediluco and plunges into the Nera gorge below.
Around the origin of the waterfall, there is a legend:
A fairy creature, a nymph named Nera, fell in love with the shepherd Velino.
It was difficult for them to date because they belonged to too different worlds.
Juno, furious, transformed the nymph into a river for having transgressed the rule that did not allow falling in love with a human being. Velino, in desperation, threw himself into the Marmore cliff, believing that Nera was drowning. Jupiter, to avoid certain death, transformed him into water, so as to be saved and reunited with Nera for eternity.
The flora and fauna present is typical of the Mediterranean scrub. The importance of the biodiversity of the place is evidenced by the SIC recognition and Special Protection Area of the Natura 2000 European Ecological Network. There are unique species in Italy such as the dipper, the yellow wagtail, the white wagtail and the kingfisher.
Over time the water has dug caves of stalactites and stalagmites in the travertine and today some can be visited accompanied by a speleological guide. In addition to this, other visits are offered, both naturalistic and at night.