5 June is the Day of the breakthrough of the naval mining blockade of Leningrad.

On this day, 5 June, 1946, the first safe route to the Baltic Sea was laid in the Gulf of Finland, among the minefields. The hydrographic department of the Red Banner Baltic Fleet of the USSR Navy informed seafarers about the opening of navigation along the Great Ship Fairway from Kronstadt to the Tallinn-Helsinki fairway. The Leningrad sea port has again started operating at full capacity. The city, which survived terrible trials, returned to peaceful life.

Before opening the fairway, four divisions of minesweepers passed through it. (A minesweeper is a special-purpose ship whoch task is to search, detect and destroy sea mines and guide ships (vessels) through minefields.)

Mine clearance works in the Gulf of Finland, which began in the autumn of 1944, ended in early June 1946. Full mine clearance works continued until 1963.