Norwegian Air Shuttle (www.norwegian.com) has launched a sale to Oslo, Stockholm, and Copenhagen in May and June 2014, primarily from NYC and Ft Lauderdale. Some sample fares:

NYC to Oslo: $363
Ft. Lauderdale to Oslo: $$564

NYC to Stockholm: $400
Ft. Lauderdale to Stockholm: $516

NYC to Copenhagen: $446
Ft. Lauderdale to Copenhagen: $521

It should be noted that Norwegian Air Shuttle is a low-cost carrier, where you do have to pay for checked bags and for meals onboard…but at these prices, it’s still a great opportunity to visit this area of the world.