Oslo Gardermoen Airport is Norway’s most important airport and handles more than 25 million passengers a year. It serves as a hub for SAS, Norwegian Air Shuttle and Wideroe. You can get to various destinations worldwide, and there are often great deals available when departing from Oslo.
Norwegian, by the way, is always a good starting point when searching for connections to Oslo.

Houston: €306 Star Alliance Flights From All over Europe (€406 With Luggage)

Toronto & Montreal: €369 Air France Premium Economy From Scandinavia

Washington DC & Chicago: Air France Premium Economy Starting at €425 From Oslo

Montreal & Toronto: €391 British Airways Premium Economy from Scandinavia

Munich: Lufthansa Flights From Various European Cities Starting at €85 (€118 With Luggage)

Bali: €427 KLM Flights From Oslo (€497 With Luggage)

Cape Town: €1,352 Air France Business Class Flights From Oslo

Singapore: €1,083 Business Class with LOT From Stockholm

Singapore: LOT Flights From 4 European Countries Starting at €386 (incl. Luggage)

Addis Ababa: Ethiopian Business Class From Oslo Starting at 332€

Bangkok: €480 Nonstop From Scandinavia, Italy, Brussels with Thai

Qatar Business Class: €1,418 to Asia from Scandinavia

Mexico City: Oneworld Premium Economy Flights From Amsterdam & Scandinavia Starting at €702

Asia: Starting at €1,114 in Business Class From Oslo With Etihad

Tokyo: €445 from All Over Europe with Qatar Airways (incl. Hold Bags)

Sydney: €2,294 Qatar Airways Business Class from Stockholm & Oslo

Phuket, Thailand: €1,345 for Business Class With Etihad Airways From Oslo

Boston: €680 for BA Premium Economy From Oslo & Gothenburg

Hi Belgium Pass: Roundtrip with Brussels Airlines, Unlimited Train Rides for €169
