Airport hub guide
Seattle Tacoma International SEA: the complete layover guide
One terminal, four concourses, two satellites, one free underground train, everything airside. Here is how to spend a layover at SeaTac without stress.
Layover verdict Strong for 2 to 6 hour layovers because every gate sits behind a single security perimeter and the train makes any concourse reachable in minutes; weaker overnight, when checkpoints close until around 4 a.m.
Best lounge play The two Club SEA locations, near gate A12 and near gate S9 in the South Satellite, take Priority Pass. If you carry the right Amex, the 14,000 square foot Centurion Lounge above the Central Terminal food court is the prize.
The one thing to know Once you clear security at SEA you never screen again. The SEA Underground train connects all concourses and both satellites airside, so a gate change is a short ride, not a new ordeal.
Last reviewed 18 May 2026
Quick facts
SeaTac at a glance
| Terminals | 1, with Concourses A to D plus the North and South Satellites |
| Airside transit between terminals | Yes, the free SEA Underground train links all concourses and both satellites with no security rescreening |
| Free wifi | Yes, unlimited, on the airport's official free network in all public areas |
| Sleep friendliness | Fair. Landside stays open 24 hours, but checkpoints close late evening and reopen around 4 a.m.; no dedicated sleep rooms |
| Lounge count | 12, including 3 Alaska Lounges, 2 Delta Sky Clubs, 2 Club SEA locations and the Amex Centurion Lounge |
| Nearest in terminal hotel | None inside the terminal; the closest hotels are minutes away by shuttle from the parking garage courtesy islands |
Orientation
How SeaTac is laid out
SeaTac is one building doing the work of four: a single terminal shaped like an X, with the Central Terminal in the middle, Concourses A to D running along the legs, and two satellite buildings standing alone out on the airfield.
The south side of the X holds Concourses A and B plus the South Satellite. The north side holds Concourses C and D plus the North Satellite. Concourse A has 16 gates and hosts Delta, United and a run of international carriers. Concourse B has 17 gates shared mainly by Delta and Southwest. Concourses C and D and the 20 gate North Satellite belong largely to Alaska Airlines, which calls SeaTac home. The 14 gate South Satellite handles most international long haul departures, British Airways and Japan Airlines among them.
The connective tissue is the SEA Underground, the free automated train running beneath the terminal. It links all four concourses with both satellites and it runs entirely airside, so changing buildings never means a new security screening. This is the single biggest thing SeaTac gets right. A gate change that would cost an hour at a multi terminal hub costs minutes here.
Security is the honest weak spot. Typical waits run 10 to 25 minutes, but peak windows in the early morning, midday and late evening can push the general lines to 30 to 40 minutes. The free SEA Spot Saver program lets any departing passenger reserve a screening time slot between 4 a.m. and 10 p.m., no membership required. Use it. It is the cheapest queue skip in American aviation.
Getting downtown is genuinely easy. Link light rail leaves from a station beside the parking garage; from baggage claim, head up one floor near carousel 16 and cross Skybridge Six. Trains run every 8 to 10 minutes and reach Westlake Station in the heart of downtown Seattle in about 38 minutes for a $3 adult fare. With 5 hours or more between flights, Pike Place Market is a realistic outing.
Concourse by concourse
What each part of SEA gives you
Concourses A and B
Concourse A is Delta territory and the deepest lounge corridor in the airport. Two Delta Sky Clubs sit here, one near gate A1 open from 4:15 a.m. to 11:15 p.m. and one near gate A11 open from 5 a.m. to 10:30 p.m. The Club SEA near gate A12 takes Priority Pass and runs from 5 a.m. to midnight, making A the default stop for Priority Pass holders. Concourse B next door is the quieter Southwest and Delta workhorse with fewer reasons to linger.
Concourses C and D
This is Alaska Airlines country, and Alaska Lounges operate in both Concourse C and Concourse D. Note the catch: Alaska Lounges ended their Priority Pass partnership back in 2021 after overcrowding, so entry now runs through Alaska Lounge membership or eligible tickets. If your plan was Priority Pass into an Alaska Lounge, your plan is out of date by five years.
The North and South Satellites
The North Satellite holds 20 gates and a third Alaska Lounge, and it serves Alaska flights almost exclusively. The South Satellite is the international building, home to 14 gates and the second Club SEA near gate S9, open 6 a.m. to midnight and on the Priority Pass network. Both satellites are train only, so budget the ride when your board flashes a gate starting with N or S.
The Central Terminal
The hub of the X holds the main food court and, on a mezzanine level above it, the American Express Centurion Lounge. Rebuilt in 2023 at 14,000 square feet, more than triple its old footprint, it runs daily from 5 a.m. to 10 p.m. and admits Amex Platinum and Centurion cardholders. It still fills up at peak times despite the expansion, so arrive early in your layover rather than late.
Your layover, planned
The SEA guides
SeaTac layover guide, hour by hour
What 2, 4 and 6 hours actually buy you at SEA, and when a Link light rail run to Pike Place Market is realistic. At 5 hours it usually is.
Every SEA lounge and how to get in
The full table: three Alaska Lounges, two Delta Sky Clubs, both Club SEA locations and the Centurion Lounge, with access methods and hours.
Sleeping at SeaTac
The honest sleep map: what the overnight checkpoint closure means for your plan, where the quieter corners are, and which nearby hotels are worth the shuttle.
Priority Pass at SEA
Both Club SEA locations explained, when they hit capacity, and why the Alaska Lounges no longer count toward your membership.
SEA transit and connection guide
Minimum connection times, the satellite train playbook, and what to do when your inbound lands late. Built for the tight connection sweat.
Check lounge access for SEA
Twelve lounges operate across SeaTac, from the Priority Pass friendly Club SEA pair to airline and credit card lounges. Compare current access options, prices and hours before you fly.
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FAQ
SeaTac layover questions
Can I sleep overnight at SeaTac airport?
The landside public areas stay open 24 hours, but security checkpoints close late in the evening and reopen around 4 a.m., so plan to wait landside if you arrive between screenings. There are no dedicated sleep rooms. The nearest real beds are airport hotels a short shuttle ride from the courtesy islands on the third floor of the parking garage.
How do I get between concourses and the satellites at SEA?
Take the SEA Underground, the free automated train beneath the terminal that links Concourses A through D with the North and South Satellites. It runs airside, so there is no new security screening when you change buildings. The four main concourses also connect on foot through the terminal.
Is wifi free at SeaTac?
Yes. Join the airport's official free network anywhere in the terminal for unlimited access. It is regularly ranked among the faster airport networks and holds up for video calls in most gate areas.
Which SEA lounges take Priority Pass?
Two: The Club SEA near gate A12 in Concourse A, open 5 a.m. to midnight, and The Club SEA near gate S9 in the South Satellite, open 6 a.m. to midnight. The three Alaska Lounges left the Priority Pass network in 2021, and the Centurion Lounge admits only Amex Platinum and Centurion cardholders.
Can I leave the airport and see downtown Seattle during a layover?
Yes, with about 5 hours or more between flights. Link light rail runs from the station by the parking garage to Westlake in downtown Seattle in about 38 minutes for a $3 adult fare, with trains every 8 to 10 minutes. Budget the return ride plus security, which can hit 30 to 40 minutes at peak times.
How long does security take at SEA?
Typical waits run 10 to 25 minutes, stretching to 30 to 40 minutes during early morning, midday and late evening peaks. The free SEA Spot Saver program lets you reserve a screening time slot between 4 a.m. and 10 p.m. with no membership. TSA PreCheck and CLEAR lanes also operate at the checkpoints.
Nearby
Related airports
Portland International (PDX)
Alaska's other Pacific Northwest base, a short hop south. Smaller, calmer, and a completely different pace of layover.
Vancouver International (YVR)
The Canadian neighbor to the north. Connecting between SEA and YVR means crossing a border, so treat it as two separate journeys.
San Francisco International (SFO)
The big United hub down the coast and a common alternate routing for West Coast itineraries.
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