A danlayer was a type of vessel assigned to minesweeping flotillas during and immediately after World War II.
A dan is a marker buoy which consists of a long pole moored to the seabed and fitted to float vertically, usually with a coded flag at the top.
Dan laying was an important part of minesweeping, and boats were fitted specifically for this purpose.
Since Germany had been an exponent of mine warfare since the 1920s, it was natural that the Kriegsmarine used a number of danlayers during World War II.
In 1944, prior to the Allied invasion of Normandy, the Admiralty-type Motor Mine Sweepers Nos.