March 17, 2022
Late to your gate? Don’t let a mad dash across the terminal derail your travel experience. Sometimes the quickest way to your destination at Seattle-Tacoma International Airport (SEA) is to go underground. SEA trains have always had the ability to get you across the terminal in a snap and help you access the N and S Concourses, and now the airport’s train system has a new name.
Allow us to reintroduce the airport’s train system as the SEA Underground! Hop on board and mind the gap with these tips and tricks. Next stop: SEA Underground!
Fast Facts on SEA Underground:
- Know before you go: Each airline leases different gates around the terminal. Depending on your airline you’ll be able to narrow down where you need to go to board your flight! Alaska Airlines flies out of C, D, and N gates. Delta, United, and almost all international airlines fly out of the S and A gates. See a full list of airlines and their gate assignments
- Get to all gates: The A, B, C, and D Concourses are all connected and you can walk or take the train to any of those four. To get to the N and S Concourses, you’ll have to take SEA Underground since they’re not connected to other gates
- Made it through security? Find the nearest train station to you. Checkpoint 2 is the closest checkpoint to the S Train Loop while Checkpoint 5 is the closest to the N Train Loop. Or use our interactive map for step-by-step directions!
- Hop on for a quick ride: In a rush? Even though you can walk to each gate outside the N Concourse and Concourse S, you can easily take a train to get to your destination quicker! Each train ride is two to five minutes long. A timer on top of each train estimates the arrival of the next train
- Don’t exit by mistake: When exiting the train, if you’re continuing on to your flight, make sure to steer clear of all baggage claim signs! If you pass an airport employee in front of a desk on the SEA Underground level, you’re more than likely going to exit out of the secure area. Need to exit? Head to the Concourse S or N for two options to exit from the secure area
Ride the rainbow
The SEA Underground consists of three lines and each is assigned a different color — the Blue Line (South Train Loop), the Yellow Line (Shuttle train between A and D stations), and the Green Line (North Train Loop). The lines are easy to identify by the corresponding color on the walls next to and behind the station doors (And don’t worry! SEA is working on adding more signage soon!) In the meantime, here’s a quick cheat sheet:
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Yellow Line (Shuttle train between A and D stations)
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This line connects to Concourse S and N Train Loops to help you travel quickly to all the other gates! It only has two stops to and from the A and D stations so make sure you get off after one stop. Otherwise, you’ll be back where you started.
Blue Line (South Train Loop)
The South Train Loop connects the A, B, and S Concourses (in that order). The resin flower artwork, Flower Wall, by Nancy Blum is located above the entrance for the South Train Loop at the A Train Station.
Green Line (North Train Loop)
The North Train Loop connects the D, N, and C Concourses. A set of oil paintings,Travelor by Kare Gantz, are located above the entrance for the North Train Loop at the D Train Station.Underground amenities
Learn what you can find at each SEA Underground station. For more guidance, use our interactive map or download the flySEA app.
| Station and Train Line | Amenities | |
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 Blue Line (South Train Loop) Yellow Line (Shuttle train between A and D stations) |
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Blue Line (South Train Loop) |
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Art |
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Blue Line (South Train Loop) |
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 Green Line (North Train Loop) Yellow Line (Shuttle train between A and D stations) |
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Green Line (North Train Loop) |
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Restrooms |
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Green Line (North Train Loop) |
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Art |
Want to learn more?
- Check this out: User’s Guide to the Train for more tips on the SEA Underground
- Here to help: Information booths staffed by volunteers are located at both the A and D train stations. They can help point you in the right direction
- More art: Learn more about artwork at SEA Airport
- Maps and app: For more guidance or information on any location, visit our interactive map or download the FlySEA app
