The profusion of silver mines in Kongsberg's hinterland is known collectively as Sølvgruvene. The easiest way to visit is with the tours that leave from the signposted Kongsgruvene, 700m from Saggrenda (8km south of Kongsberg along the road to Notodden), from where you'll ride a 2.3km rail along the stoll, a tunnel painstakingly chipped through the mountain to drain water from the mines. The main shaft of the largest mine plunges 1070m into the mountain, down to 550m below sea level.
Constructed without machinery or dynamite – the rock was removed by heating it with fire, then throwing water on the rock to crack it – the tunnel moved forward at 7cm per day and took an incredible 73 years (from 1782 to 1855) to complete.
Inside, visitors are guided around equipment used in the extraction of silver, including an ingenious creaking and grinding lift and work area on 65 wet and slippery ladders.
The admission price includes a bus ride from outside Kongsberg's tourist office. Travellers with disabilites and children under three are not allowed to enter the mines for safety reasons (it's also not recommend for under fives). Bring warm clothing as the underground temperatures can be a chilly 6°C.
Other activities organised in and around the mine include learning how to mint your own coins (sadly though we're yet to find a bank willing to accept the ones we made) and a crash course in digging a mine in your own garden. With advance reservation you can join a rope-and-torch tour.