The Fv108 runs 3.8 kilometres in tunnel from the mainland in Østfold into Hvaler, out to Asmaløy. The tunnel opened on 2 October 1989, after four quick years of planning and building.

It reaches 120 metres below sea level, and the steepest gradient is 10 percent. The tunnel and the bridges out through the island group replaced the Skipstadsand and Korshavn ferry crossing, and gave Hvaler a ferry-free road all the way to Kirkeøy.

Hvaler is among the largest destinations for outings in Østfold, and the summer traffic goes through the same tunnel. When it closes everyone must detour, so check the status before you drive.