Stockholm’s strategic Cold War stronghold

The archipelago’s southernmost island was once home to a terrifyingly intricate – and nearly invisible – system of state-of-the-art military installations. Only a few survive.

Our ferry slid through the gunmetal-grey waters of the Baltic Sea. Granite outcroppings scattered around us, bald except for tufts of trees and the occasional bird; on the horizon, I could see only more rock, more sea, more mist. We were approaching the end of the Stockholm archipelago. It felt like we were approaching the ends of the Earth.

The Stockholm archipelago, Sweden’s largest, is made up of some 30,000 islands that scatter east and south of the city, into the Baltic. Some of the islands are popular summer retreats, their shores thick with resort towns, souvenir shops and vacationing Swedes.

But I wasn’t headed to any of those. I was going to Öja, the archipelago’s southernmost island – home to one of the Cold War’s most advanced military batteries, which was off-limits to the public until January 2013. Getting there requires riding the entire 70km length of a commuter rail line, switching to a 23km bus route through winding roads and thick forests and taking a 4km ferry ride from Ankarudden harbour, on the island of Torö. It’s a journey that takes nearly three hours from central Stockholm.

At first glance, the 4km-long, 500m-wide island doesn’t seem worth the effort. It’s home to 20 year-round residents and a bird observatory. But Öja was also once home to a terrifyingly intricate system of 38 state-of-the-art military installations that were buried almost invisibly, across the length of the island, ready to defend Sweden from an attack. Today, five survive – including the elaborate Cold War battery that could hit a target 27 km away and withstand a nuclear blast five times the one that levelled Hiroshima.

Not that you’d have any idea from simply being on the island.

Our ferry squeezed into the harbour, looking so unlikely to fit that I braced myself for the sound of scraping metal. The lack of people on the shore made it easy to find Jaak Kriisa, an older man with a cheerful face and a firm handshake. Kriisa is the island’s resident military expert, former tank company commander and, as he put it happily, “5% of the island’s population!”. With warm greetings, he helped me into his golf cart – one of the most convenient methods for getting around Öja – and off we went, rattling along the dirt road that serves as the island’s main artery.

Our first stop was the Cold War bunker known as the Landsort Battery. Tucked among boulders and bushes, an army-green cannon protruded from a hump of granite. Nearby, hidden between rocks, a camouflaged door lead into the earth. The site didn’t look like much, but Kriisa gestured to a map just outside. Like a rabbit’s warren, an entire world lay beneath our feet, running four storeys down and 18m deep. Finished in 1977 and used until the Cold War’s end in 1991, the battery was supported by a crew of 325 men – as well as anti-aircraft artillery and machine guns that could shoot well beyond the horizon.

“This was the most advanced artillery in the world during the Cold War,” Kriisa told me, unlocking the door. Tours run regularly in high season, but it’s wise to email Kriisa directly to ensure English options before you visit.

Originally, there were six coastal batteries in Sweden, each equipped with three 12cm guns, all built to deter invasion during the Cold War. The Landsort Battery is the only one left.

Tiny Öja, it turns out, stands in a crucial location. It marks the entrance to several sea routes to Stockholm, making it a key point of defence for the nation. Despite Sweden’s neutrality in the Cold War, the country feared that, in the case of a US-Soviet conflict, the Soviets would roll across Europe from the east. So Sweden built a network of high-tech, expensive artilleries exactly like this one. “We know the battery was a success, exactly because it was never used!” Kriisa said, chuckling.

A “hot war”, a conflict involving actual fighting, was a frightening prospect for everyone, including the neutral Swedes. At the time, 20% of the Swedish budget went to defence. (Today, it’s less than 2%.) The Landsort Battery alone cost 600 million krona to build. The country had the world’s fourth-largest air force. And every building in Sweden with more than one family was ordered to build bomb shelters by law.

Kriisa and I went through two sets of doors, each with walls 1.5m thick. The first, he said, was built to withstand the shock wave that would be caused by a nuclear blast. The second was to keep out the gas. A shower stood just inside, ready to rinse any soldiers unlucky enough to be exposed to the blast.

Down another level, we walked through the bathroom, the bunks and into the kitchen, where the walls glowed with 1970s shades of green and orange. Everything had been left just as it was in 1991. When I opened one of the cabinets, I found an ancient jar of coffee, its grounds fossilised into a single chunk.

Heading back up to the top level, we paused in the artillery room. Ammunition sat stacked against a wall, ready to be loaded into the gun dock. Following Kriisa, I squeezed through a small door and looked up: a metal ladder ascended another storey high, up into the tower that held the cannon I’d seen from outside. Hand over hand, I climbed.

Sitting next to one of the largest guns I’d likely ever see up close, legs swinging, I marvelled at little Öja’s chutzpah – and at how hidden the island’s defences were.

Later, I borrowed a creaky bike from Kriisa and pedalled to the island’s southern tip. The Landsort Lighthouse, the largest in the archipelago and the oldest in Sweden, loomed above me, blinking green at ships in the distance. A cannon aimed south; behind it sat a cement pillbox. On the rocky shoreline far below, two other cannons sat alert. Öja’s first defence installation, built in 1933, this artillery and bunker was used during World War II, in the same way the Cold War battery would later be used: as deterrence. It too never saw action. The Landsort Battery replaced it in the 1970s and was decommissioned in 2009.

Circling the lighthouse, heading inland, I stepped carefully along granite boulders, admiring the wild coastline, its rocks dotted with little red houses. Some 30m away from the pillbox, I looked down and paused. There were metal bolts beneath my feet.

I was walking on a bunker, and I hadn’t even noticed.

By helping to deter both Axis powers and Soviets, Öja had helped win two wars for Sweden. By now, I realised, I should not be surprised by what I might find on this tiny, rocky islet in the Baltic Sea.