The names, without the confusion
Older accounts open with a tangle of etymology and then give up. It is simpler than they make it.
The Swedish parliament decided to fortify the islands in 1747 and work began in 1748. The fortress was named Sveaborg — the Swedish castle — in 1750, which Finnish speakers rendered as Viapori. After independence it was renamed Suomenlinna, the Finnish castle, in May 1918. One fortress, three names, and the politics of the country in each of them.
The man to know is Augustin Ehrensvärd, who directed the building and is buried in the Great Courtyard, where his tomb is one of the sights. Older accounts never name him.
What it was for, and the two days it failed
It was built to hold the eastern approach to Sweden against Russia, at a scale meant to make Helsinki the naval base of the Baltic. It is often described as having been finished a dozen years after it started. It was not: work went on in phases for over a century and the design was never completed.
Two episodes matter, and British readers have a stake in both.
- 1808: it surrendered. In the war that took Finland from Sweden, the garrison capitulated to the Russians after a few months' siege, without the fortress being taken by assault — an outcome argued about in Finland ever since. Suomenlinna spent the next hundred and ten years as a Russian base.
- August 1855: the Royal Navy bombarded it. An Anglo-French fleet shelled the fortress for some forty-five hours on 9, 10 and 11 August 1855, during the Crimean War — the Baltic campaign that most British accounts of that war leave out. The damage is still visible, and the same war supplied the brick for Uspenski Cathedral from another fortress the same fleet destroyed.
Getting there
- The public ferry leaves from the eastern side of the Market Square, in front of the Presidential Palace. Suomenlinna is in fare zone A, so any ordinary city ticket covers it; it is public transport, not a tour. The crossing takes about fifteen minutes, with several departures an hour in summer and at least one an hour in winter. The ferry is ice-strengthened and runs through the ice season. Tickets must be bought before boarding.
- There is also a private waterbus, and city tickets are not valid on it. It runs early May to late September, takes about half an hour, and its advantage is that it calls at the King's Gate pier at the far end of the islands, which lets a visitor land at one end and walk back to the ferry at the other. It has its own fares.
What is open, and what is shut when
Landing is free and the fortifications are free, every day of the year. The ramparts, the bastions, the King's Gate, the dry dock — one of the oldest still working anywhere — and Ehrensvärd's tomb cost nothing and need no booking.
The museums are another matter, and most of them are seasonal.
- Suomenlinna Museum — open all year, and the one to see if only one is open. Covers the whole two and a half centuries.
- The submarine Vesikko — summer only, mid-May to the end of September. Shut for the winter, and not accessible to wheelchair users; getting into a submarine involves a hatch and a ladder.
- The Military Museum's Artillery Manege — May to the end of September.
- Suomenlinna Church — charges admission in high summer, and see below.
- The Customs Museum is free, with limited hours.
Anyone arriving between October and April should expect the fortress itself and one museum, which is still a good half-day. Older accounts list a toy museum; it appears to have closed and should not be counted on.
The church, which is also a lighthouse
This is the best single fact on the islands. The church was built in 1854 as a Russian Orthodox garrison church, dedicated to Alexander Nevsky, to a design by Konstantin Thon. After independence it was converted to Lutheran use on a 1928 plan by Einar Sjöström, which took off the onion dome and squared the tower — so the building reads as neoclassical now and was not.
Its tower is a working lighthouse, and its light flashes the letter H in Morse code — four dots — for Helsinki, to shipping coming in from the Gulf of Finland.
People live here, and some of them are prisoners
Suomenlinna is a residential district of Helsinki with about eight hundred residents and some four hundred people working on the islands. The practical consequences: quiet hours from ten at night to seven in the morning, residential areas signposted, and a marked Blue Route laid out to keep visitors on the public ground and out of private gardens. Following it is the courtesy the place runs on.
There is also an open prison on the islands, with around ninety places, whose inmates work on the fortress — masonry, grounds, restoration — and can take vocational qualifications while doing it. A good deal of the stonework a visitor admires was repointed by them.
Rules worth knowing before arriving
- No open fires, barbecues, disposable grills or camping stoves, anywhere, at any time of year. This is absolute and it surprises people who assume Finnish outdoor rights apply. No camping and no tents either.
- Cycling is allowed on the main routes but not on the ramparts, with a twenty-kilometre speed limit.
- Nothing is to be dug, climbed on or chipped off the fortifications or the cannon.
- Dogs on leads, and not on the beach or in playgrounds; assistance dogs anywhere.
- The official beach is between Kustaanmiekka and Susisaari, and the warning attached to it is real: large ships pass close in Kustaanmiekka bay and the currents they throw are dangerous.
Two changes since any older account
- The fortress is run differently. On 1 January 2026 the Governing Body of Suomenlinna was merged into the Finnish Heritage Agency and now operates as a department of it. Services and staffing are unchanged, but descriptions of an independent agency are out of date.
- Bridge works. The renovation of the Susisaari bridge, the busiest on the islands, was put back to 2026 after problems with the procurement, and a temporary bridge stands alongside. Attractions and services are unaffected.
About a million people come every year, two in three of them from abroad, almost all in summer. The declared strategy is not to grow the summer figure but to spread visits into the colder half of the year — which is as good an argument as any for going in October.