The biggest draw to the island is its unique and fascinating military history. Even the winter ferry transporting visitors to the island is a re-purposed military vessel. Isosaari has been a military stronghold since the Russian era and saw its heaviest fighting against the British Navy during the Crimean War of 1854-56. The grave of a British soldier who died in the attack (supposedly the only casualty on the opposing side) is still located on the island.
In slightly more recent history, Isosaari played an incredibly grim role when it served as a prison and concentration camp during the Finnish Civil War of 1918, holding up to 1,500 prisoners from the pro-Russian red side – many of whom died there. A monument to the prisoners was erected on the island in 1955.
Despite still being owned by the Finnish army, Isosaari was almost entirely abandoned and became semi-derelict until recently when the state decided to turn it into a tourist destination, with regular ferry services leaving from Helsinki harbour. At first these tours only operated during the summertime, but they proved to be so popular during their first season that they have now been extended to the winter months as well.
In less than a year, the island has already become a covert spot for urban explorers, since much of it is still overgrown and the old military buildings are almost frozen in time. While some places are still off limits, you can still see the run-down bunkers, gun range, canteen, the torpedo test station, surveillance towers, and underground tunnels. The more you explore, the more secrets you can uncover.
But the island is also a relaxing spot for those looking to get out of the city for the day. There are lovely beaches with stunning views of the Baltic Sea and the Helsinki coastline, a restaurant, lots of wildlife, public saunas, fishing spots, a campsite, picnic spots, and even a golf course. The 40-minute boat trip to the island is also a great experience, passing by the Suomenlinna fortress and many other islands on the archipelago.
The schedule for the ferry may change in the future if the island becomes more popular. Currently, the winter schedule lasts up until May Day and runs from 10am until 3pm on Wednesdays, Fridays, Saturdays, and Sundays. During the summer, the ferry is more frequent and runs from 9:30am, but it is still recommended to book tickets in advance as they can sell out quickly. The island has a guest marina, so you can also get there via a private boat. On Mondays, the ferry is only available for golf cruises. The boats leave from the harbour just off the Market Square and adult tickets cost around €18 each.
Everything on the island can generally be seen in a single day and there are maps available from the restaurant. Whether you want a relaxing getaway or to learn more about Finnish history, Isosaari is definitely worth a day trip.