The stock game comes with a variety of Submarines to command if you choose a U.S Career or a Type 9 U-boat if you choose a U-Boat career.
Standard Silent Hunter 4 Features Historically Inspired Player Vessels
7.1.4 Rockin Robbins Airplane Avoidance.
5.1 The Fall of the Rising Sun Ultimate Mod.3.2 Historically Inspired IJN, USN, Axis, Allied & Merchant Vessels.3.1 Historically Inspired Player Vessels.2.2 Known Bugs, Issues,(and possible fixes).