This crosses several bridges and intermediate islands before finally accessing the island of Muskö through the Muskö Tunnel [sv], a 3 km (1.9 mi) long road tunnel running some 70 metres (230 ft) under the sea.

[1] During the Cold War the underground facility was kept highly secret and not much information about it was known to the public.

In the autumn of 2019, as part of an upgrade of defence facilities and manpower, the naval base was revived, and it was announced that it would also serve as seat of the main headquarters of the Swedish Navy.

[4] One of the Swedish submarine incidents in October, 1982, took place just off Muskö Naval Base.

[5][6] A survey carried out in 2000 concluded that sedimentation in the tunnels leading to docks contained PCBs, organotin compounds and heavy metals, mainly mercury and copper.