Since early 2013, the German Navy has been using a ViSTIS® solution for training operators in the use of the compensating and ventilation systems for the second batch of HDW Class 212A submarines. The scope of training incorporates visualization of all spaces and systems relevant for instruction purposes as well as evaluation of the individual training results. In addition to a true-to-life virtual presentation of the main areas on board the HDW Class 212A submarine, more than 25 different scenarios were developed to cover complex switching and operating tasks for the ventilation and compensating systems. Integrated simulation of the technical processes ensures that the virtual submarine reacts to the trainee's input in a realistic way. In combination with the very realistic graphical visualization this provides for smooth transfer of the acquired abilities to the real submarine. In training scenarios the trainee submariner must show the ability to implement correctly what has been learned so far. Use may be made of a multi-level help function that allows, for example, information to be found about the next switching step or provides an overview of the system to be operated.