Here's a picture of the SH4MissionEditor screen:
The "dots" are waypoints where a single, or group of ships will change direction, and the "lines" are the path they follow in between those waypoints. Notice that few groups follow the exact same path, and that since these files are different for each given time period in the game, and there are separate files for the various "types" of groupings, such as Convoys (usually more than 2 ships with escorts), Merchants (generally one and two ships), Task Forces, Troop Ships & of course "local" traffic as in the image, the "variety" encountered can seem quite realistic. Initially, the Japanese followed "shortest route" from Point A to Point B early in the war. As time passed, and the US subs finally started getting detonations from their torpedoes, the Japanese added more escorts and changed their routes, which the game is then able to somewhat emulate in the files. Dependent upon the mod, you will eventually encounter fewer and fewer mid-ocean groupings, and find more and more traffic in closer to shore, but you will also find small PT boats, other smaller vessels, and of course, more airplanes "guarding" the shipping. What the game is incapable of is a realistic hydrophone and sonar suite on the escorts and other vessels. The sea state does influence their efficiency, but there is no shallow water reflections to help hide you. Islands, reefs and shorelines do not hide your presence (same with radar), and after a depth charge detonation, the escorts can still hear you, even with add-in mods that attempt to "fix" that. It is just a short-coming of the game, that really isn't noticed much under most normal circumstances. You can attempt to emulate Fluckey, O'Kane, Cutter, Morton, and even Beach and all his illustrious commanders, but you will not have quite the same experience... In some ways, the AI is "smarter" than the Japanese were, other times it is dumb as a box of rocks, but that's what you get with software AI that emulates a human...
