Torghatten is a granite dome on the island of Torget in Brønnøy Municipality in Nordland county, Norway. It is known for its characteristic hole, or natural tunnel, through its centre. It is possible to walk up to the tunnel on a well-prepared path, and through it on a natural path.

On 6 May 1988, Widerøe Flight 710 from Namsos Airport to Brønnøysund Airport crashed into the side of the mountain, and all 36 passengers and crew died.

Tunnel

Torghatten is a mountain located along the coastal area of northern Norway that features a distinctive natural tunnel passing completely through it. According to legend, the hole was made by the troll Hestmannen while he was chasing the beautiful woman Lekamøya. As the troll realized he would not overtake her, he released an arrow to kill her, but the troll-king of Sømna threw his hat into the arrow's path to save her. The hat turned into the mountain with a hole in the middle.

The tunnel measures 166 metres in length, with an average width of 18 metres and an average height of 41 metres, and sits about 115 metres above current sea level at its midpoint. The mountain consists of foliated granite of Proterozoic age, with the foliation (layered structure of the rock) oriented almost vertically, creating natural weakness zones that have facilitated erosion processes.

For many years, the prevailing hypothesis attributed the formation of the tunnel primarily to wave action from the North Atlantic Ocean. However, research by Jakob Johan Møller and Per Tore Fredriksen published in the Norwegian Journal of Geography suggests a more complex origin. Their investigation revealed a lack of rounded cobbles and boulders that would typically indicate significant wave erosion. Instead, they documented several features suggesting glacial influence, including ice-sculptured bedrock on the hillside approaching the eastern entrance, an elongated uphill-curving channel likely formed by subglacial meltwater, polished areas on the northern wall inside the tunnel, and slightly rounded bedrock obstacles within the tunnel. These features are consistent with what geologists term "p-forms" (plastically-moulded forms), which develop through ice flowing under pressure and high-pressure meltwater flowing beneath glaciers.

  • Brønnøy municipality website about Torghatten