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Suomenlinna Sea Fortress & Lonna

 JT-Line’s waterbus operates this route during the summer season 2021:

    • Helsinki Market Square (Kolera Basin) > Lonna > Suomenlinna (Artillery Bay) > Suomenlinna (King´s Gate) > Lonna > Helsinki Market Square


Suomenlinna is a maritime fortress located very close to Helsinki. It is a UNESCO World Heritage Site and one of Finland’s most popular tourist attractions. Suomenlinna is also one of the districts of the City of Helsinki and home to 800 year-round residents.

The history of the Suomenlinna fortress is closely tied to the history of Finland and the Baltic Sea. The fortress was built in the mid-18th century to serve as a cornerstone of the eastern defences of the Kingdom of Sweden, to which Finland then belonged. The fortress was taken by Russia at the beginning of the 19th century. Under Russian rule it guarded the shipping lanes leading to St Petersburg together with naval bases in Tallinn and Kronstadt. In 1917, Finland became independent and took over the maritime fortress the following year. Suomenlinna offers something to see and experience for visitors of all ages: rich and varied nature, fortifications, artillery, tunnels, museums and many cafés and restaurants.

The waterbus service by JT-Line operates between the Kolera Basin stop by the Market Square and Suomenlinna (Artillery Bay and King´s Gate) from 8th May to 30th September 2021.

More information on Suomenlinna can be found on the website:


Lonna is a small island situated between the Market Square and Suomenlinna that was opened to the public in summer 2014. The island has been the site of a sea mine depot and later a demagnetisation base, among other things. The demagnetisation base was in use from the Continuation War right up to the 1960s, as there were a lot of sea mines in Finnish territorial waters which were set off by the magnetic fields in ships’ hulls. The demagnetisation station’s equipment reduced these magnetic fields. Today Lonna has a cosy restaurant and café. The old demagnetisation equipment is on display for visitors in an exhibition area in the restaurant.

The waterbus service by JT-Line operates between the Kolera Basin stop by the Market Square and Lonna from 20th May to 30th September 2021.

More information on Lonna can be found on the websites (unfortunately only in Finnish):

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