While there's no ferry from Stockholm to the capital of Norway, Oslo is just a short plane ride away!
If you have the time (and the money) try one of the many helicopter tours offered in the city or go to one of Norway's many fjords and small villages in the surrounding area.
But if you only have the time for a quick stop, Oslo itself still offers plenty of things to see and do. Amongst other things Oslo offers a great collection of Viking age items and ships. And if you can, make a quick visit to the city's unique Opera House!
Approx 1 hour flight from Stockholm