Cheapest one-way flights from Seattle to Keflavik in December from $438

AirHint found the following cheapest one-way flights from Seattle (SEA) to Keflavik (KEF) in December 2025 (see full year).

One-Way flights

31 Dec Lufthansa
14 Dec Icelandair
27 Dec Sun Country Airlines
30 Dec Icelandair direct
31 Dec Icelandair direct
16 Dec Hawaiian Airlines
14 Dec Icelandair direct
27 Dec Icelandair direct
16 Dec Icelandair direct

Also check the deals for return flights from Seattle to Keflavik in December.

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