How to Fly to Europe From the US for Under $100 One-Way

Traveling to Europe from the US just got cheaper—if passengers are willing to forgo all frills and travel light. Budget Icelandic airline PLAY has announced $99 flights from the US to Amsterdam, Berlin, Copenhagen, Dublin, Liverpool, Paris and Reykjavik. They are bookable as single legs of a round-trip flight, for travel in October to March 2025, with departures from East Coast airports in the Boston, New York and Washington areas.

But there’s a catch: The airfares will be available only as part of a flash sale from Sept. 26 through Oct. 3, and the airline isn’t revealing how many are ...