Ekkodalen on Bornholm is Denmark's longest rift. It stretches 12 km from Vallensgård Mose through Almindingen, Flæskedal, Kløvedal and Kelseådal to Saltuna on Bornholm's northeast coast.
Wikipedia https://en.wikipedia.org/wiki/Ekkodalen
Coordinates 55°6'25.524" N 14°53'53.375" E
