Silent Hunter III
I played the first silent hunter for Nintendo. That was almost 20 years ago. When this game came out I went into a frenzy to get my hands on it. Amazingly enough I was thoroughly impressed. (Ubisoft is notorious for forcing game release dates even with an unfinished product). There are a few bugs that later patches fixed.
The game is absolutely massive. If you want to take the time you can travel for days and still not get to your destination, however the ability to speed up time is awesome! It is difficult enough to make you want to try and learn all the controls but easy enough for the casual gamer to enjoy. The hardest part of the game is not the controls but implementing the tactics required to take down those hard-to-kill destroyers!
This game is about as close to real as you can get
I was deployed in 5 submarines in the 60's and know a few things about actual maneuvering, targeting and avoidance. This game is awesome. The realistic settings can make it as real as you want to get. Typically a sub only got one chance at a warship before hauling a.. or getting sunk and sometimes no matter what you did you just couldn't get away. We were pinned on bottom a few times in real life. From target id to plotting a shot this game is super. Enjoy it.