A public sauna has opened on the former military island of Lonna, just off the shores of Finnish capital Helsinki.

Designed by Helsinki-based architects OOPEAA, the compact 190sq m sauna has been built using natural materials – including handcrafted, untreated wooden logs.

Located within a seven-minute boat ride of Helsinki city centre, the sauna has been designed to offer a natural haven within a metropolitan environment.

“The sauna represents the border between urban and nature, between the busy life of the city and the open landscapes on the sea,” said Anssi Lassila, OOPEAA’s architect in charge of the project.

“With views framing the silhouette of the city on one side and opening towards the see on the other, the Lonna Sauna is part of the historical continuum of the tradition of public saunas in Finland.”

Heated with wood-burning stoves the Lonna Sauna recreates the “calm and almost sacred feeling of the traditional Finnish sauna”, while placing it in a new, contemporary architectural frame.

There are separate bathing areas for men and women and a terrace – directly accessible from the sauna rooms as well as from the outdoor shower space – bridges the sauna with the seashore.

Public saunas were omnipresent in Finnish cities up to the mid-1980s, and acted as social meeting places for people who had often moved into urban settings from rural areas.

After a decline in the number of public saunas throughout the 1990s and 2000s, however, there has been a renewed interest in the tradition in recent years.

“Public saunas were lively places and numerous throughout the country,” Lassila added. “But today there is only a few of them left.

“However, in recent years, there has been a renewed interest in the tradition of public saunas and a number of new public sauna buildings have opened in various parts of the city in Helsinki.”

The island of Lonna used to be occupied by the military and only recently opened to the public.

It is owned by the Governing Body of Suomenlinna, but a group of entrepreneurs leased it out in 2013. Since taking over, the group has added a restaurant, a café and a number of other services to Lonna, as part of plans to revitalise island life within the Helsinki archipelago.

The Helsinki archipelago includes hundreds of islands, varying from uninhabited islets to large islands, which house some of the capital city's suburbs.

Lonna – one of the smallest islands in the Helsinki waters – is located close to the larger Suomenlinna island, which is a UNESCO World Heritage site and popular with tourists and locals.

The Lonna Sauna is open to the public throughout the summer months.