AirHint found the following cheapest return flights from Seattle (SEA) to Keflavik (KEF) in March 2026 (see full year).

Return flights

09 Mar - 17 Mar	Lufthansa
16 Mar - 24 Mar	Lufthansa
23 Mar - 30 Mar	Lufthansa
23 Mar - 31 Mar	Lufthansa
12 Mar - 20 Mar	Lufthansa
30 Mar - 07 Apr	Lufthansa
29 Mar - 06 Apr	Lufthansa
25 Mar - 02 Apr	Lufthansa
04 Mar - 12 Mar	Lufthansa
09 Mar - 26 Mar	Icelandair	direct
27 Mar - 03 Apr	Lufthansa
13 Mar - 20 Mar	Lufthansa
20 Mar - 27 Mar	Icelandair	direct
05 Mar - 13 Mar	Lufthansa
26 Mar - 02 Apr	Lufthansa
26 Mar - 03 Apr	Lufthansa
31 Mar - 08 Apr	British Airways
25 Mar - 02 Apr	Icelandair	direct
25 Mar - 01 Apr	Icelandair	direct
26 Mar - 02 Apr	Icelandair	direct

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

The deals are updated regularly. The prices may go up as tickets are purchased by other travellers. Only the cheapest flights are offered. Select a price to book and secure these cheap prices.

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Cheapest return flights from Seattle to Keflavik in March from $527

Return flights