Newish low-cost carrier Norse Atlantic has fares to Europe from $110 one way right now — meaning it's probably cheaper to fly to Europe than to another city in the US. These are some of the lowest one-way fares we've seen to Europe in the past few years, but it's good to keep in mind that if you're traveling with more than a backpack, you'll need to pay for luggage.
This sale is set to end September 26th, so make sure to book before then.
The cheapest fares we've found are on the New York, JFK to London, LGW route:
You can read more about the sale on Norse's website — keep in mind that it ends on September 26th!
Once you're in London, Berlin, or Oslo, it's generally easy and cheap to book flights or take a train to other European destinations.