The Western Harbour (Swedish: Västerhamn) is one of two harbours in the port of Mariehamn, the regional capital of Åland, in the Archipelago Sea part of the Baltic.

[6][7][8] With an average of 15 daily ferry sailings,[9] and approximately 20 international cruise ships visiting Mariehamn each year,[4] the Western Harbour is the third-busiest international passenger port in Finland with c. 1.25 million annual passenger arrivals (2.5m total passenger movements) in 2018.

[2] The harbour remains ice-free most winters, or is only covered by thin ice.

[2] The museum ship Pommern, a four-masted iron-hulled sailing ship built in 1903, is moored in the Western Harbour as an exhibit of the Åland Maritime Museum.

[10] Mariehamn's other harbour, the Eastern Harbour (Swedish: Österhamn, Finnish: Itäsatama), is mainly used for smaller leisure boats and yachts, and is one of the largest leisure marinas in the Nordic region.