The scuba diving vessel HMS Spårö discovered the mine line in mid-May.
The mines were known before, but not the exact position.
“We had a maritime surveillance unit in the area, so it was a good idea to investigate this particular site to ensure that the mines are not located in any of the anchorage areas.
We can state that the mines fortunately do not and there is no direct danger to the public as long as they remain untouched ", says Carl Lundvall, head of the 42nd mine clearance division at the fourth naval battalion, on the Armed Forces' website.
Risks can not be ruled out in connection with trawling, diving and underwater work.
The navy is therefore working on a plan for how the mines will be handled.
The mines are of the type MK16 and were felled in 1940. A total of 175,000 mines were felled in the Baltic Sea and the North Sea during the two world wars.
About 50,000 remain, according to the Armed Forces.