Lærdalstunnelen

World longest tunnel, over 24 km long, connects Aurland and Lærdal. The lighting inside the tunnel is outstanding, makes whole experience of driving 15 miles under solid rock pretty special. There are several caves along the tunnel, allowing you to take a short break and snap pictures if you want to (yes, please, absolutely).
It's about 20 min drive, very convenient and rather scenic drive between towns (visiting Stave Church in Lærdal!)

If your going to flam you probably have to drive through this tunnel....THE LONGEST TUNNEL IN THE WORLD. The only other option is that ridiculously narrow and dangerous scenic route that goes up and down the mountain. Beautiful scenic drive BUT really really dangerous. Unless your a really good driver (and keep in mind most car rentals in norway are stick shift) I would avoid this route. If your a good drive like me that can drive up and down narrow and curvy mountain roads only made to be a one way street but somehow fit 2 cars with one tire sticking off the road and dangling over the mountain and similar dangerous situations where you can't see if a car is coming around the corner while driving stick shift, you better take that challenge because the glaciers at the top, the flat valley areas, the grass covered roof houses, the goats and sheep and cows to see, waterfalls, etc. Oh, and keep in mind the scenic road takes a while (2 hours prob with all the stopping for the sight seeing- this is the road you take to see the fjord lookout point)

For those that can't or don't want to take the time/have the time the tunnel is the faster way/short cut and safer.....well, if you don't fall asleep (thats why the gov. actually put lights in the tunnel, to keep people from falling asleep). This tunnel is the longest tunnel in the world. 20 minutes roughly. Its really long, dark most the time, boring, etc. lol, its a tunnel. Three sections with lights though which is cool.

Overall, its the longest tunnel in the world and the fastest and safest way to flam from oslo or even the ski area hemsedal (that direction lol).