The Type VII is the most produced type of submarine in history. It is a diesel submarine armed with torpedoes, a deck gun, and some anti-air weaponry. Today it is seen as simple, but back during the Second Weltkrieg it was revolutionary. Hundreds were produced, some of which made their way to Oceanyka through getting lost or boarded in action in the Pacific Theatre. There, the venerable U-Boat was reproduced ad infinitum.
As a submarine, the Type VII is specialised at hunting down capital ships and cargo vessels, taking them out with a distance with its acoustic torpedoes. However, it is fairly weak to dedicated anti-submarine tactics and equipment. This is especially true for the Type VII; most anti-submarine manuals in the world were created specifically to destroy this kind of submarine, and the world's technology has progressed far beyond the Type VII.