"The Þríhnúkagígur crater is close to the mountain range Bláfjöll, where the capital region’s ski resort lies. It was first explored in 1972, when cave expeditioner Árni B. Stefánsson was roped down with a single lamp mounted to his helmet. Many years later this unique work of nature became a legend among Iceland’s mountaineers and cave explorers who were up to the task of lowering themselves down the small black opening, through the bottleneck and all the 120 meters to the bottom of the dome.
In June 2012, tourists were given the opportunity to partake in such an expedition for the first time, with the Inside the Volcano tour, run by the tour operator 3H Travel. A specialized lift was installed and travelers were lowered into the crater. The company’s managing director Björn Ólafsson calls the crater a ‘diamond in the rough’ and believes it has the potential to become as big an attraction as the Blue Lagoon"
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