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

Return flights

01 Apr - 06 Apr	Lufthansa
03 Apr - 07 Apr	Lufthansa
07 Apr - 14 Apr	Icelandair	direct
04 Apr - 09 Apr	Icelandair	direct
13 Apr - 20 Apr	Icelandair	direct
01 Apr - 06 Apr	Icelandair	direct
03 Apr - 07 Apr	Icelandair	direct
23 Apr - 30 Apr	Icelandair	direct
03 Apr - 10 Apr	Icelandair	direct

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

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 April from 572€

Return flights