Coordinates: UTM 33W 0367507 7249908, 65°20'42.2''N 12°9'10.2''E
Primary interests: Tourism, education
A raised shoreline seen as a large field with rounded stones 40-50 m.a.s.l. A marked path leads the way through a dark forest, that suddenly opens up for this area with rounded stones. As if the fairy-tale atmosphere was not there already, there are old legends about a treasure buried under the stones at Triborgen. A large delegation came to Sømna in 1887 to dig for the treasure. However, it was never found. Today the area is protected as a Cultural Heritage and no digging is allowed.
This site is one of the most well known attractions in Sømna. It is visited both by local people and by tourists, and there is a marked trail and information board about the geology.