All Aboard the SEA Underground

Late to your gate? Don’t let a mad dash across the terminal derail your travel experience. Most times the quickest way to your destination at Seattle-Tacoma International Airport (SEA) is to go on the trains in the terminal. SEA trains have the ability to get you across the terminal in a snap and help you exclusively access the N and S Concourses.

Allow us to introduce the airport’s train system the SEA Underground! Hop on board and mind the gap with these tips and tricks. Next stop: Wherever you need!

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 Air Lines, United Airlines 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 the gates: The A, B, C, and D Concourses are all connected and you can walk or take the train to any of them. To get to the N and S Gates, 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. Checkpoints 1, 2, and 3 are the closest checkpoint to the Blue Train Line or the South Train Loop while Checkpoints 4, 5, and 6 are the closest to the Green Train Line or the North Train Loop. Even if you’re on opposite ends of the airport, the Train Loops can be accessed from the Yellow Line Shuttle at the A and D Stations, but using the interactive map for step-by-step directions is the best way to navigate in confidence!
• Hop on for a quick ride: In a rush? Even though you can walk to each gate outside the N and S Concourses, you can easily take a train to get to your destination quicker! Each train ride arrives every three minutes
• Don’t exit by mistake: If you’re connecting on to your next flight, make sure to steer clear of all baggage claim signs! If you pass airport staff in front of a desk on the SEA Underground level, you’re likely going to exit out of the secure area. If you need to exit? go to the A and D Stations.

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 on the digital signage. Here's a quick cheat sheet:

There are three trains at SEA, the YELLOW Line, the BLUE Line, and the GREEN Line

YELLOW LINE (Shuttle train between A and D Train Stations only)
The Yellow Line transfers to the other train lines and helps you to get to the other side quickly! It only has two stops to and from the A and D Train Stations so make sure you get off after one stop. Otherwise, you’ll be back where you started. The next train you’re looking for is likely across from this one after you’ve Ridden the Yellow Line!

YELLOW LINE Underground amenities

Station and Train Line	Amenities
Blue Line (South Train Loop to S, B, and A Gates) Yellow Line (Shuttle train between A and D stations only)		Sensory Room The Interfaith Prayer and Meditation Room Exit to Baggage Claim
Green Line (North Train Loop to N, C and D Gates) Yellow Line (Shuttle train between A and D stations only)		Mamava Nursing Pod Exit to Baggage Claim

BLUE LINE (South Train Loop)
The Blue Line connects the S, B, and A 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.

BLUE LINE Underground amenities

Station and Train Line	Amenities
Blue Line (South Train Loop to S, B, and A Gates)		Art
Blue Line (South Train Loop to S, B, and A Gates)		Mamava Nursing Pod Pet Relief Area

GREEN LINE (North Train Loop)
The Green Line connects the N, C, and D Concourses (in that order). A set of oil paintings,Travelor by Kare Gantz, are located above the entrance for the Green Line at the D Train Station.

GREEN LINE Underground amenities

Station and Train Line	Amenities
Green Line (North Train Loop to N, C and D Gates)		Restrooms Water Refill Station Pet Relief Area
Green Line (North Train Loop to N, C and D Gates)		Art

Learn what you can find at each SEA Underground station. For more guidance, use our interactive map or download the flySEA app.

Want to learn more?

• Here to help: Information booths staffed by airport staff and volunteers always ask for help and they can 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