STS Sedov (Russian: Седов), formerly Magdalene Vinnen II (1921–1936) and Kommodore Johnsen (–1948), is a four-masted steel barque that for almost 80 years was the largest traditional sailing ship in operation.

Magdalene Vinnen II was at the time the world’s largest auxiliary barque and exclusively used as a cargo ship with a crew that was partially made up of cadets.

Until her last voyage as Magdalene Vinnen II in 1936, the ship sailed to Argentina, South Africa, Australia, Reunion and the Seychelles.

She came under Russian state ownership after the surrender of Germany — on 20 December 1945, the British handed over the ship to the Soviet Union as war reparation.

Based at the Baltic Division of Training Ships in Riga she embarked cadets from schools of navigation of Kaliningrad and Murmansk.