For centuries and up until the end of the Cold War foreigners were unwelcome in the Stockholm archipelago as Sweden worried about invasion and spying submarines.
But since the fall of the Iron Curtain, most of the cannons and the signs forbidding foreigners on the archipelago's shores have disappeared, and more foreigners are starting to find their way out into the archipelago.
This year Visit Sweden, an official center for tourism and travel information, has noticed a growing number of visitors from Sweden's neighboring countries, but also from Germany, France and Holland, its information director, Bo Soderstrom, said.
Cissi Grape of Visit Skargarden, an association for archipelago businesses, said a weak local currency, the crown, and cheap travel have boosted the interest.
"We are seeing a big jump," she said, adding that even Britney Spears took time off to see the archipelago while on tour in Stockholm a few weeks ago.
"But for most people the archipelago is still a white spot on the map," she continued, referring to a U.S. ship captain who recently sailed through Stockholm in the world spanning Volvo Ocean Race and wondered why he had never heard of it or its challenging sailing before.
The archipelago's barren, windswept islands and islets, shaped by an ice sheet for centuries during the Ice Age, and its lush, quiet bays with centuries-old oaks have attracted people for thousands of years. Permanent communities with small fishing villages were established by the Viking era while mining of iron ore flourished in the 12th century.
But it was not until the middle of the 19th century that the archipelago opened up to a wider public, when steamboats started to traffic the islands. The wealthy and cultural elite built grand and airy villas in white, yellow and green, that stood in stark contrast to the small signature red or grey (unpainted) wood houses of the poorer locals.
Katherine Moreau, a vacationing engineer from Paris, was surprised to discover the expansiveness of the archipelago.
"This must be Sweden's best kept secret. You can travel by boat for hours, and there are still more islands on the horizon," she said as she returned to Stockholm from a trip out to the island of Uto.
Archipelago Tourism Increasingly Popular Among Swedes
Today, it is a popular summer holiday destination for Swedes. Many thousands have summer houses on the islands, and just as many make day trips or stay for a few days, drawing on a vast network of ferries, hostels and B&Bs.
A wide range of tastes and needs are met here -- from renting exclusive yachts and dining at Michelin star restaurants to camping in tents by the seashore or renting a bed in the Spartan pilot tower turned B&B on the remote island of Landsort.
Popular activities include sailing, swimming and sunbathing, along with fishing, bicycling, hiking, riding, island hopping and kayaking in the outer archipelago. Lunching or dining on one of the 35 steamboats that leave Stockholm for archipelago tours is also popular.
But according to Sverre Rolfson, an avid sailor and father of three, the main attraction of the archipelago is its unique nature. The sea and the ever-changing light that can have varying psychological effects -- sometimes soothing, sometimes unsettling, he said.
"It is both wild and picturesque. You know that you will have exciting and varied adventures here, all in a relatively safe environment," he said one warm summer's evening on his sailing boat in the port of Nynashamn.
Klas Helmersson, the former director of the Vasa Museum in Stockholm that exhibits the only intact 17th century ship ever salvaged, said it was the combination of moving on water and the inherent allure of the islands that has made him sail the archipelago for more than 30 years.
"It is the fascination of always discovering new things and the contrasts between the sea and the islands," he said, adding that his favorite place is the barren, "somewhat forbidding" outer portion of the northern archipelago around the islands of Rodloga and Svartloga.
Islands Inspire Artists, Writers, Filmmakers
The nature has also long inspired Sweden's painters, writers and filmmakers. Ingmar Bergman filmed "Summer with Monica" on the island of Orno, and the "Seacrow Island" books, by "Pippi Longstocking" writer Astrid Lindgren, were adapted to the screen on Norrora.
August Strindberg, one of Sweden's most famous writers, lived on the island of Kymmendo in the 19th century, and not only wrote about its inhabitants in the national epic "Natives of Hemso", but also painted its grim and grey winter storms.
It might seem strange that the Stockholm archipelago was unwelcoming to foreigners for so long, but perhaps it's not surprising considering its history. The fear of a sea invasion was sparked by a Russian attack in 1719 that erased entire fishing villages and farming communities. It was further fueled by World War II and the ensuing Cold War.
The 16th century fortress town of Waxholm, dubbed "the capital of the archipelago," gives testimony to this threat. The Waxholm Citadel and Fortress museums show the development of the Swedish defense in the archipelago during the last 500 years. Close by, Siaro fortress museum exhibits cannons and trenches above ground, and a center of command, kitchen and barracks below ground.
In a secret program during World War II, Sweden even used the island of Galo to train seals, otters and eagle owls to detect submarines and prime explosive devices.
But these days there is little concern over a Russian invasion, Grape said.
"The only real invasion we are seeing today is the pilgrimage of tourists to the island of Sandhamn," she said pointing to the interest in the internationally best selling crime novels by the late Swedish journalist Stieg Larsson.
Larsson's protagonist has a fictitious summer house in an old missionary station in the picturesque sailing hub of Sandhamn -- apparently enough to attract visitors from other shores.
Grape expected a planned U.S. screen adaptation of the books would only increase the interest in the archipelago.
"A Hollywood film would certainly put the archipelago on the map. I think we can expect even more foreigners in the future."