Cheapest return flights from Seattle to Keflavik in December from $495

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

Return flights

31 Dec - 15 Jan Lufthansa
03 Dec - 10 Dec Icelandair direct
31 Dec - 13 Jan Lufthansa
31 Dec - 15 Jan Icelandair direct
31 Dec - 13 Jan Icelandair direct
09 Dec - 16 Dec Icelandair direct
05 Dec - 12 Dec Icelandair direct
07 Dec - 14 Dec Icelandair direct
31 Dec - 07 Jan Icelandair direct
27 Dec - 17 Jan Air Canada
17 Dec - 24 Dec Southwest Airlines
16 Dec - 27 Dec Icelandair
15 Dec - 21 Dec Alaska Airlines
11 Dec - 18 Dec Icelandair direct
15 Dec - 22 Dec Icelandair
27 Dec - 17 Jan Icelandair direct
04 Dec - 01 Jan Icelandair
21 Dec - 28 Dec Sun Country Airlines
14 Dec - 03 Jan Icelandair
14 Dec - 03 Jan Icelandair direct

Also check the deals for one-way flights from Seattle to Keflavik in December.

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