You Can Now Book Joint Southwest–Icelandair Tickets — Here’s How

Southwest Airlines’ partnership with Icelandair is officially live, and connecting flights on the 2 airlines are available for booking. This is a big deal for Southwest flyers, especially since the airline traditionally hasn’t had partnerships with other carriers.

Let’s see what this means in practical terms.

What Is the Southwest-Icelandair Partnership?

Southwest—the largest airline in the U.S. by domestic passengers carried—and Icelandair aren’t in any of the 3 airline alliances spanning the globe. Their partnership isn’t an alliance per se, either, but a so-called interline agreement. This allows the partners to connect passengers and luggage seamlessly across their different systems.

What this means for travelers is that they now can book flights with connections between Southwest and Icelandair, but only via Baltimore-Washington International (BWI). 

Denver (DEN) and Nashville (BNA) will be added in the future, although it is unclear when.

Baltimore was chosen because it is a large base for Southwest and is served by Icelandair.

Southwest has hundreds of daily flights between Baltimore and dozens of destinations across the U.S., the Caribbean, and Central America. Those flights can act as a feeder for Icelandair’s daily nonstop flight to Reykjavik (KEF) from Baltimore.

From Reykjavik, passengers can continue to Europe on Icelandair’s network spanning the continent. The availability of connecting flights via the partnership was first reported by The Points Guy.

Booking Flights With the Southwest – Icelandair Partnership

To book, you will need to head to the Icelandair site; the Southwest website does not currently provide this option, but it will be available in 2026. The flights can also be booked on some third-party sites.

A sample booking from Nashville (BNA) to Reykjavik via Baltimore shows that Southwest flights booked on the Icelandair site carry Icelandair flight numbers.

Service classes that can be booked include Saga class, Icelandair’s version of business class, but that only applies to the segments actually flown on Icelandair since Southwest has only economy seating.

Continuing to a European destination can be cheaper than stopping in Iceland. For example, a booking from Nashville to Copenhagen (CPH) was significantly less expensive than ending a trip in Reykjavik.

Connecting via Baltimore and Reykjavik is, however, a complicated way to get to Europe.

From major U.S. airports, the larger European gateways are at most 1 stop away; adding an extra stop is cumbersome unless there is a significant price difference.

Going via Reykjavik could also be attractive for travelers who want to take advantage of Icelandair’s stopover program for no additional airfare and spend a few days in the country.

Final Thoughts

The Southwest-Icelandair partnership is undoubtedly good news for travelers, but it currently has relatively limited usefulness.

Flights to Iceland and onwards to Europe can only connect via Baltimore, and passengers can’t earn or redeem Rapid Rewards points…yet. Once those 2 issues are resolved, which should happen in 2026, the partnership will become far more interesting for U.S.-based travelers.