If you need to stretch your legs, Hallingporten at Gulsvik by the lake is a natural stop - about two hours from Oslo. There's a café, petrol station, and you can swim in Lake Krøderen on warm days. The place has been a rest stop for travellers for decades.
The tunnel just ahead has an odd shape - look up and you'll see what appears to be a second tunnel above the road. That's exactly what it is. The upper section is the original railway tunnel from the Bergen Line, built when the railway reached Gulsvik in 1908. In 1972 the railway was rerouted through a longer tunnel further into the mountain, and this old rail tunnel was converted for road traffic.
Gulsvik was actually the temporary end of the Bergen Line for a year. From here, passengers transferred to boats across Lake Krøderen, then took another train from Krøderen station to continue towards Oslo. When the final section was completed in 1909, the whole line opened.
The name Hallingporten - the Gate to Hallingdal - is fitting. This narrow passage has always controlled access to the valley. In April 1940, Norwegian soldiers held positions here against advancing German forces. The steep terrain and old rail tunnels gave good cover. On 24 April, German infantry with tanks pushed through after heavy fighting. The bridges were blown that night and Norwegian forces retreated up the valley.