Suomenlinna sea fortress and ferry: HSL tickets, opening hours and what to see

💡 The Short Version: Suomenlinna is a UNESCO World Heritage sea fortress on six islands in Helsinki’s harbour. Entry to the grounds, ramparts and tunnels is free. The HSL ferry leaves Market Square (Kauppatori) every 15 to 20 minutes all year, takes 15 minutes and costs a Zone AB ticket. Six museums operate on the islands: the Suomenlinna Museum and Military Museum are open all year, and Submarine Vesikko from mid-May to September. Follow the marked Blue Route from the ferry quay to the coastal artillery at Kustaanmiekka and the King’s Gate. Or book a tour: a Suomenlinna Museum ticketad is €10, and a return ferry ticketad is €10.

⚠️ No tickets are sold on board. Buy a Zone AB ticket or a 12-hour Suomenlinna return at the ticket machines on Market Square or in the HSL app before you board. Travelling without a valid ticket risks a penalty fare.

Ferries compared: HSL ferry or private waterbus

Two boat services run from Market Square, from different piers:

The HSL ferry is ice-strengthened and keeps running through sea ice between January and March.

History and layout: Sveaborg and Viapori

The Swedes founded the fortress in 1748, when Finland was part of the Kingdom of Sweden, and called it Sveaborg (“Sweden’s Castle”); in Finnish it was Viapori. The Swedish military engineer Count Augustin Ehrensvärd designed it as a naval stronghold to guard Sweden’s eastern flank against Russia.

It surrendered to Russian forces in 1808 during the Finnish War, after which Finland became an autonomous Grand Duchy under the Tsar. After independence in 1917 it was renamed Suomenlinna (“Castle of Finland”). About 800 people live on the islands in preserved wooden garrison cottages and old naval barracks.

Suomenlinna Church. Photo: Nemo bis, Wikimedia Commons, CC BY-SA 4.0.

Walking the Blue Route: key sights

The Blue Route (Sininen reitti) is a 1.5-kilometre walking route from the northern ferry pier to the southern tip, marked with blue signposts:

1. The Jetty Barracks (Rantakasarmi)

Your ferry docks beside the long, curved pink facade of the Jetty Barracks, a bomb-proof granite-and-brick building from 1868 to 1870. It holds the Suomenlinna brewery restaurant (Panimo), the Jetty Barracks Gallery and artist studios.

2. Suomenlinna Church (Suomenlinnan kirkko)

Up the gentle cobbled hill to the south is Suomenlinna Church. It was built in 1854 as a Russian Orthodox garrison church with five onion domes and converted to a Lutheran church in the 1920s with a new neoclassical tower. The steeple holds a navigational beacon for shipping in the Gulf of Finland.

3. The Great Courtyard (Suuri linnanpiha)

The Great Courtyard on Susisaari island was designed by Ehrensvärd as the administrative and ceremonial centre of Sveaborg. In the middle stands the neoclassical stone Tomb of Augustin Ehrensvärd, carved by the Swedish sculptor Johan Tobias Sergel on the commission of King Gustav III.

Great Courtyard and Ehrensvärd’s tomb. Photo: Jisis, Wikimedia Commons, CC BY-SA 3.0.

4. Submarine Vesikko

Vesikko, on dry land on the eastern shore of Susisaari, is a prototype submarine built in Turku in 1933 that served as the design basis for Germany’s Type II U-boats. It served in the Finnish Navy in the Winter War and Continuation War and is the only surviving Finnish submarine from World War II. You can step inside the narrow hull to see the diesel engines, electric steering motors and torpedo tubes (open mid-May to September; one ticket also covers the Military Museum, €10 for adults, sotamuseo.fi).

Submarine Vesikko. Photo: Zache, Wikimedia Commons, CC BY-SA 4.0.

5. Kustaanmiekka ramparts and tunnels

South across the timber footbridge is Kustaanmiekka (Gustav’s Sword). Sand and turf earthworks cover unlit granite tunnels, gunpowder magazines and vaulted bastions, and black iron coastal guns installed by Imperial Russia in the late 19th century line the southern bluffs.

You may explore the ramparts and passages. Bring a phone torch for the darker tunnels.

Coastal artillery on the Kustaanmiekka ramparts. Photo: Michal Pise, Wikimedia Commons, CC BY 2.0.

6. King’s Gate (Kuninkaanportti)

The King’s Gate at the southern tip of Kustaanmiekka was the ceremonial sea entrance to Sveaborg. It was built in 1753 to 1754 on the spot where King Adolf Frederick of Sweden anchored to inspect the fortress works. The two-storey portal has gun embrasures, royal emblems and an inscription carrying Ehrensvärd’s warning: “Stand here upon your own ground, and do not rely on outside help.”

Museum admissions and opening hours

The islands, ramparts and parks are free, but six museums charge or have their own tickets:

All six museums accept the national Finnish Museum Card (Museokortti). The Helsinki Card covers entry to the Suomenlinna Museum, Ehrensvärd Museum, and Military Museum Manege, as well as the municipal HSL ferry.

Practical visitor advice

• Footwear: The paths are uneven cobbles, dirt trails, granite stairs and grassy slopes. Wear trainers or boots with grip, not dress shoes.
• Wind: The fortress is exposed to the open Gulf of Finland, and the wind is strong even in summer. Bring a windbreaker; in winter add a hat, windproof mittens and insulated footwear.
• Food and drink:
  • Cafe Silo: A bright Scandinavian cafe near the Russian merchant quarter serving pour-over coffee, sourdough toasties and cardamom rolls.
  • Suomenlinna Brewery Restaurant (Panimo): In the Jetty Barracks, serving craft ales, salmon soup and cured game.
  • Valimo: A summer bistro in an old torpedo workshop in the guest marina on Susisaari.
  • Picnics: Bring food from Market Square to eat on the grassy Kustaanmiekka ramparts. Barbecues and open fires are forbidden on the islands.
• Accessibility: The cobbles and steep earthworks make the Blue Route hard for wheelchairs and heavy pushchairs. The visitor centre has a map of an alternative route on paved roads and gentler gradients between the northern quay and Suomenlinna Centre.

What to explore next

• Back at Market Square: Carl Ludvig Engel’s neoclassical centre is across the street; see Helsinki Cathedral and Senate Square.
• Other islands: Waterbuses go to Vallisaari, Lonna and Pihlajasaari; see the Helsinki archipelago islands guide.
• After the walk: Allas Sea Pool or Löyly, in the Helsinki public saunas guide.
• Tickets and passes: the Helsinki public transport guide and the Helsinki Card review.