Are you in Stockholm and admire maritime history? In such case, if you like to travel for longer distances, try to travel to the island of Arholma. The island is the last stop when taking a ferry from Stockholm. Also, you can take a bus to Norrtaelje (Norrtälje) and from there another bus where Simpnaes Brygga (Simpnäs Brygga) is the last station.
Arholma is famous for its “battery” or Batteri Arholma museum, created after the Cold War. But before that museum, there is another museum based in Simpaes called Arholma Maritime Museum. This museum is an open-air type. It has a small building that is open only during July-August during weekends. This is partly since the museum is organised voluntarily.
For more information, you can get in touch with the museum’s society. Enjoy Roslagen!