**For an afternoon downtown, I’d book luggage storage near Westlake station or Pike Place Market.** You can collect your backpack afterward and take the light rail toward Sea-Tac.

- **Downtown storage:** [Bounce](https://bounce.com/luggage-storage/seattle) has participating shops and hotels around Pike Place, downtown, and King Street Station. These are staffed bag-drop locations. Many currently advertise rates from **$3.95 per bag per day**, though the total depends on the location, bag size, and fees. Book online and check the pickup hours.
- **Light rail lockers:** I couldn’t find public luggage lockers at Link stations. The lockers Sound Transit advertises are for [bicycle storage](https://www.soundtransit.org/ride-with-us/know-before-you-go/bikes-scooters/parking-storing-your-bike).
- **At Sea-Tac airport:** [Smarte Carte baggage storage](https://www.portseattle.org/services-amenities/baggage-services) is between baggage carousels **9 and 10**, open **7 a.m.–10 p.m.**, with breaks **11:30 a.m.–noon** and **6–6:30 p.m.** No reservation is required.

Given your route, downtown storage would avoid an extra trip to the airport. Check that your booking covers a large backpack and that the shop stays open until you’re ready to leave.