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

Return flights

30 Oct - 08 Nov	Icelandair
31 Oct - 07 Nov	Icelandair
21 Oct - 28 Oct	Finnair
22 Oct - 29 Oct	Finnair
29 Oct - 05 Nov	Finnair
01 Oct - 08 Oct	Finnair
07 Oct - 14 Oct	Finnair
20 Oct - 27 Oct	Finnair
08 Oct - 15 Oct	Finnair
16 Oct - 23 Oct	Finnair
12 Oct - 19 Oct	Finnair
13 Oct - 20 Oct	Finnair
10 Oct - 17 Oct	Finnair
27 Oct - 03 Nov	Finnair
26 Oct - 02 Nov	Finnair
25 Oct - 01 Nov	Alaska Airlines

Also check the deals for one-way flights from Seattle to Helsinki 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.

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Cheapest return flights from Seattle to Helsinki in October from 451€

Return flights