One of Finland's smallest lighthouses illuminates the sea by the ruins of Gustavsvärn Fortress

The fortress of Gustavsvärn, near Hanko, was built at the turn of the 18th and 19th centuries. However, its duration was short-lived after it was destroyed by the Russians in the mid-19th century. Although a fixed navigational signal light was built from the ruins of the fortress, it too was destroyed after World War II. The lighthouse, which was later established on the site, still guides seafarers in the vicinity.

The Hanko Peninsula fortifications were built on three islands

In the 18th century, an important east-west sea route passed through the Gulf of Finland. The coast was systematically fortified after the beginning of the great power struggle between Sweden and Swedish-held Finland, and Russia. The Swedes built fortresses along such military sea lanes as military hubs.

Over the centuries, the Hanko Peninsula and surrounding islands have been strategically important areas for Finland's shipping and defence. The archipelago off Hanko was a natural protection zone for a city facing towards the sea.

In 1792, the King of Sweden officially ordered the construction of the Hanko sea-fortress chain. Fortresses were built on three islands. The Gustavsvärn Fort is the best preserved of these. It was part of the same defence chain as the Suomenlinna Fortress off the coast of Helsinki and the Svartholma Fortress in Loviisa.

Blueprint drawings of the Gustavsvärn Fortress.

The Gustavsvärn Fortress was built to last

The construction of the Gustavsvärn Fortress, three kilometres southwest of Hanko, began in 1789. The fortress was mainly made of red granite, cut from the island's local rock. There are still many traces of quarrying on the island to this day.

The fortress was designed as a tiered fort based on a bastion system. However, construction ceased in the early 19th century and the fort was left incomplete. Certain structures, e.g. the artillery tower, remained unbuilt.

In 1809, after the Finnish War, the Hankoniemi Peninsula was handed over to the Russians, and the construction of the fortress continued. However, only three years later, the fortress was abandoned as it was considered unnecessary. In the 1850s, the fort was again taken into use as the Crimean War threatened, but its maintenance was considered to be too expensive. Consequently, the Russian High Command gave orders to blow up such fortresses to keep them out of enemy hands and Gustavsvärn Fortress was destroyed in 1854.

Gustavsvärn Fortress defending against an invasion by a section of the British naval fleet during the Crimean War on the 10th May 1854. Original image by Wladimir Swertschkoff.

A lighthouse rose from the fortress ruins

In 1870, a fixed navigation signal light was built inside the ruins of the fortress. It was maintained by two lighthouse guards. In addition, a foghorn siren and a siren attendant's residence were built on the island in 1900. This house is the only building remaining on the island to this day. Before World War II the island was deserted, and the lighthouse and other residential buildings were destroyed in the post-war period. The foundations of these buildings serve as a memory of their presence.

Nevertheless, the island was not without navigational lights for long because a new 11-metre-high reinforced concrete fixed beacon was built there in 1951. As one of the smallest lighthouses in Finland, it still dominates the island landscape here.

A small but interesting travel destination

The Finnish Lighthouse Society (Fin. Suomen Majakkaseura) has rented the fog siren attendant’s house on the island from Metsähallitus. This society is renovating and restoring the building to its original appearance. Throughout many centuries, rock engravings have also been made on the island.

The entire shoreline of the island is steeply sloped and with the exception of the pier, it is almost impossible for small boats to moor here. The deep basins around the island are popular with divers, as these hold many submerged wrecks. These can be explored further in the Cultural environment service window. 

Read more:

Gustavsvärn in

The Finnish Lighthouse Society

The collapsed exterior walls of Gustavsvärn Fortress.

Why and how is this location protected?

The island as a whole is considered an ancient monument and is protected by the Antiquities Act. The island has been an important part of our defence history since the 18th century. Read about Gustavsvärn in the Antiquities Register (in finnish).

The area has also been defined as a nationally significant built cultural environment, which is a part of the other military history sites in the Hankoniemi Peninsula. Check out these sites on the Finnish Heritage Agency's website.

In addition, the island is part of the Tulliniemi bird sanctuary.


The city of Hanko arranges boat transport to the island. You can also moor your own boat to the island's jetty. Visiting the island is done at your own risk. 

More about the island cruises in Hanko tourism pages! 

Finnish Heritage Agency’s mapservice

N: 6636197, E: 272450 (ETRS-TM35FIN)