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

Return flights

09 Oct - 16 Oct	Icelandair	direct
12 Oct - 19 Oct	Icelandair	direct
15 Oct - 22 Oct	Icelandair	direct
24 Oct - 31 Oct	Icelandair	direct
29 Oct - 05 Nov	Icelandair	direct
18 Oct - 25 Oct	Icelandair	direct
01 Oct - 10 Oct	Icelandair	direct
21 Oct - 28 Oct	Icelandair	direct
04 Oct - 11 Oct	Alaska Airlines
06 Oct - 13 Oct	Icelandair	direct
23 Oct - 08 Nov	Icelandair	direct
24 Oct - 08 Nov	Icelandair	direct
02 Oct - 06 Oct	Icelandair	direct

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

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.

Book a cheap hotel in Keflavik

Cheap car rent in Keflavik

Cheapest return flights from Seattle to Keflavik in October from 382€

Return flights