I've actually seen sale fares as low as $140 each way. But...
https://thepointsguy.com/2016/03/norwegian-air-787-economy-class-review/
Norwegian Air is a low-cost carrier (LCC), meaning they’ll try to add many and varied extra charges to your basic ticket. If you haven’t flown an LCC before, read this primer first.
LowFare on Norwegian is considered to be no-frills economy, and basically nothing is included except for one carry-on bag limited to 10kg. Choosing and reserving your seats (not upgrading; that’s much more expensive) will run you an additional $45 per person each way, while a checked bag is an additional $90 when purchased online or $65-$130 when paid for at the airport — and that’s just the tip of the iceberg.
I fly Norwegian regularly to Europe. One can economize tremendously, the seats are comfortable, and most important is that Norwegian staff treat you like good customers, not like cattle to be herded into cattle pens. I’ve been flying since 1950 and there are few carriers I haven’t used. IMO Norwwegian is the best value for the best flight to Europe today. AND Norwegian flies the Boeing Dreamliner which is the best plane in the air today, healthwise and comfortwise. I’ve flown to Sweden, Denmark, Norway, France and England on Norwegian. There is a reason Norwegian is voted the best low cost carrier in Europe year after year. I have never had a bad flight with Norwegian.