It was based at Riga and served with the Soviet Baltic Fleet before being used as a training vessel for crews from overseas who would be operating Foxtrot-class subs in their own navies.

After passing into private hands, and under the name U-475 Black Widow it was moored at Long's Wharf near the Thames Barrier in England where it was open to the public as a museum ship.

[1] The B- designation stands for Bolshaya (Large), and was used by the Soviet Navy during the Cold War era.

The name Black Widow and the designation U-475 were invented for the boat by the new owners.

In Soviet service it was actually known as B-49 and served in the Northern Fleet until November 1974 when it was reassigned to the Baltic.