Type 205 submarine
 The Type 205 was a class of diesel-electric German hunter-killer U-boat submarines. They were single-hull vessels optimized for the use in the shallow Baltic Sea. The Type 205 is a direct evolution of the Type 201 class with lengthened hull new machinery and sensors. The biggest difference though is that ST-52 steel is used for the pressure hull since the Type 201's non-magnetic steel proved to be problematic.