HELSINKI/BALAKLIIA, Ukraine: Visiting mayors from Ukrainian cities are among 800 delegations visiting the Merihaka civil shelter, situated in a vast underground cave carved into the rock beneath Finland's capital, Helsinki.

They took photos and were impressed by its size and capacity to hold up to 6,000 people.

The shelter is Finland's largest dual-use shelter, and has become a key showcase for Finnish companies looking to export shelter technology, especially to countries concerned about the war in Ukraine and tensions with Iran.

The shelter has a volume of 71,000 cubic meters. That's about the size of a seven-story office building. Built in 2003, it sits 25 meters underground and is used daily for sports, gym activities, and a children's playground. In an emergency, it can be converted within 72 hours by installing bunk beds, water tanks, and portable toilets.

These shelters reflect Finland's history with Russia during World War II. Because of that experience, it is still mandatory to build shelters under residential and commercial buildings above a certain size.

Finnish companies have developed strong expertise in building and maintaining such shelters. Their work includes installing radiation-proof doors, ventilation systems, emergency power, communication systems, and sewage networks.

Officials say politicians, administrators, and companies from abroad—including Saudi Aramco—have shown interest in visiting or learning more. Resilience Center Finland, established in March to promote exports, said Finland's security and defense exports are worth tens of billions of euros, with shelter sales currently in the millions and expected to grow.

Ilkka Kivisaari, CEO of Verona Shelters Group, said demand is rising so quickly that companies may soon struggle to keep up. He noted strong interest from countries such as Poland and Germany, as well as the Middle East.

Merihaka is one of 48 large and 5,500 smaller shelters in Helsinki, part of about 50,500 shelters across Finland. This network dates back to preparations made in the wake of a Soviet invasion attempt during World War II.

At another Helsinki shelter that can accommodate 3,800 people, Temet Group CEO Juha Simola arrived after a trip to the Czech Republic to promote exports. He demonstrated shelter technology to Saudi Aramco visitors and said there has been growing interest from Middle Eastern countries during the Iran conflict.

He said he received an urgent call from Abu Dhabi after a major incident, asking him to come quickly, though he gave no further details. His company is also building a factory in the United Arab Emirates, where hundreds of shelters are planned.

Temet, which has operated for 70 years, aims to earn 80 percent of its future sales from exports. Alongside major firms like Temet and Verona, smaller companies specialize in components such as blast doors and communications systems.

In Finland, shelters are required under buildings larger than 1,200 square meters. The cost of building one under an apartment block is about 1.5 percent to four percent of total construction costs.

Leaders, including Ukraine's Volodymyr Zelenskyy, Poland's Karol Nawrocki, and EU chief Ursula von der Leyen, have visited Merihaka. Poland is now investing heavily – 5.8 billion zlotys – to rebuild its shelter system after decades of neglect.

Ukraine and Poland have introduced laws requiring shelters in new buildings, but stricter rules have raised costs. Ukrainian official Yuliya Chufistova said some investors have canceled projects, showing the need to balance safety with affordability.