Southwest Airlines expands partnership with Icelandair: How to book a connection to Iceland and onto Europe

Southwest Airlines is officially expanding its partnership with Icelandair.

Next month, two additional international "gateways" will officially come online as part of the tie-up between the two carriers: Denver International Airport (DEN) and Nashville International Airport (BNA).

The upshot for travelers: You'll be able to book an itinerary that starts in one Southwest city, connect through Denver or Nashville, and then continue on via Icelandair to its hub in Rekyavik, Iceland (and even beyond to Europe, from there).

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Bookings are now open for flights departing on or after May 12.

This expansion comes after the two airlines in February launched Baltimore/Washington International Thurgood Marshall Airport (BWI) as the first airport on the U.S. side operating as part of the partnership.

Now, as TPG first reported in January, Denver and Nashville are up next.

A narrow partnership — at first

At the moment, this airline partnership — Southwest's first with an international carrier — is a bit limited, though that will change over the course of the next year.

For now, customers can book itineraries featuring connections between the two airlines using Icelandair's website, and certain third-party booking sites like Expedia (but not Southwest's website, yet).

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That means you could:

• Start a trip with a flight on a Southwest jet
• Then, easily connect onto an Icelandair flight to Rekyavik at BWI, DEN or BNA. Your bags would seamlessly transfer, too
• From there, you could even continue onward, on the same itinerary, to additional destinations in Europe.

You also can't earn or redeem Rapid Rewards points on these overseas itineraries just yet.

That's set to change in 2026 when Southwest's shift to assigned seating goes live. At that point, you'll be able to book flights to Iceland and on to Europe through Southwest's booking channels.

And you'll be able to pay cash and earn Rapid Rewards points on those bookings, or redeem points for your trip — a shift that should be a big boost for the utility of Southwest's points.

Still, the launch of this interline deal, for which TPG witnessed the formal signing earlier this year in Washington, D.C., was a major step for Southwest.

"This is an important milestone in our plan to expand how and where our customers can travel," Southwest's former executive vice president Ryan Green (who since left the company) said in January on the carrier's earnings call.

How to book through the Southwest-Icelandair partnership

In the meantime, though, we want to show you how to book a Southwest-Icelandair itinerary under the partnership as it stands right now.

Read more: Southwest quietly unveils A-List perks for new assigned-seating setup

Flights to Iceland

Starting with Icelandair's website, let's say I want to take a March round trip from Dallas Love Field (DAL) — Southwest's home airport — to KEF.

As you can see, Icelandair's website offers up an itinerary featuring one leg from DAL to BWI aboard Southwest, followed by a connecting flight over to Icelandair for the BWI-to-KEF leg of the trip.

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Alternatively, Icelandair's website may offer up a connection through Denver or Nashville, with those airports set to be included in the partnership starting in the next few weeks.

Here's an itinerary that starts in San Jose, California, featuring a Southwest flight to Denver, and a connection to Icelandair onward to Iceland.

There are similar options if you're booking through a third-party online travel agency, after Southwest recently began allowing sites in the Expedia Group portfolio to sell its flights.

The below trip includes a flight from DAL to DEN on Southwest, and then a connection onto Icelandair.

Adding Denver, alone to the interline agreement opens up the possibility of itineraries to more than three-dozen Southwest-served cities in the western U.S., the airline noted.

Booking flights to Europe

You can also technically book an itinerary to Europe through this partnership, though it may not be the most efficient way to get across the Atlantic; you'd have to go BWI, DEN or BNA, then KEF, before continuing on to Europe.

Still, it's possible.

Here's a trip that starts at Chicago's Midway International Airport (MDW) on Southwest and ends at London's Heathrow Airport (LHR).

You'd fly on Southwest to Baltimore before connecting over to Icelandair for the Reykjavik flight. Once at KEF, you could make a standard connection before the final leg to Europe — or spend a day or two (or more) in Iceland as part of a stopover; you can fit in stopovers of up to seven days.

Expansion of partnership coming soon

Less circuitous itineraries to Europe through this partnership should emerge as the airlines bring even Southwest bases online. And, the partnership should become increasingly useful to travelers as Southwest begins selling these itineraries through its own website — and especially once it allows Rapid Rewards redemptions on these trips.

Bottom line

Southwest's new partnership with Icelandair is officially live and available for bookings via Icelandair's website and some third-party sites. Though it's limited right now (and not available yet for Rapid Rewards earnings or redemptions), it'll expand significantly over the course of the next year.

During that time, Southwest also plans to announce a second international airline partner, so stay tuned.

Related reading:

• Southwest Rapid Rewards: Complete guide to earning, redeeming and maximizing points
• Best Southwest Airlines credit cards
• How to quickly earn the Southwest Companion Pass
• Southwest A-List status: What it is and how to earn it
• Maximize your airfare: The best credit cards for booking flights
• How to change or cancel a Southwest Airlines flight