I'd like to see the northern lights in Sweden, from Stockholm what are the best options to getting to Lapland (easiest, fastest, cheapest)? Any tips?
Best way is to either fly from Arlanda (Stockholm) to Luleå or catch the night train from Stockholm to Luleå. There you will find lots of nice activities.
Lapland is actually in Finland, but if you prefer to go to northern Sweden, you could go by SAS. Or, if you do want to go to Finish Lapland, try Finair. Check their website, Finnair.com for suggestions in timetable etc.
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I would go for a flight, or maybe the train. But the easiest way would probably be to take the flight to Kiruna from Stockholm. It takes around one and a half hour and it costs like 1000kr. Train might be a little bit cheaper but it will take much longer time, over 12 hours I would say.