A ball pit, 30 meters underground: Finland built an entire world against a Russian attack

Finland has built a vast network of underground shelters beneath Helsinki, including sports facilities and playgrounds, which can be converted within 72 hours into shelters for thousands of civilians in the event of a Russian attack. The main shelter, Merihaka, at a depth of 30 meters, is equipped with heavy steel doors and protection systems against chemical, biological, and nuclear threats.

Beneath the streets of Helsinki lies an underground world of gyms, sports fields, and children's playgrounds that can be transformed within 72 hours into shelters for thousands of civilians in the event of a Russian attack. Finland's extensive shelter network includes about 50,500 protected spaces with room for approximately 4.8 million people. In Helsinki alone, there are about 5,500 shelters with around 900,000 spaces. A British Sun reporter descended into the Merihaka shelter, 25-30 meters deep, where two heavy steel doors are designed to withstand explosions, and winding corridors reduce the force of the blast wave. In peacetime, the site serves as a sports center featuring football fields, badminton courts, and a play area with a ball pit. In an emergency, the equipment is cleared and 2,000 bunk beds are set up. Finnish preparedness began after the Winter War of 1939-1940 and intensified after joining NATO in 2023. Satellite images from 2025-2026 revealed the expansion of Russian bases near the border, but Western security officials stressed that the immediate threat remains limited due to Russia's involvement in Ukraine.