Question though, what would submarines do that Swordfish/Needlefish already NOT do, assuming they were playable? Submarines would have the same torpedoes as boats. They'd be slower than boats. You'd spot them via sonar, like boats. And you could just torpedo them, like boats. Depth charges went out of style post-WW2, it's all ASROCs and torpedoes nowadays.

One major difference Justin, is that submarines wouldn't be visible, or at least they'd be very tough to spot visually. Like I mentioned in the main description, boats currently are super easy to find by just scanning the horizon for a few seconds and you'll see the navigation lights clear as day. That's pretty much the biggest reason for this suggestion, is that I want that element of surprise that the current enemy boats in-game do not provide. As for detection methods, perhaps they should still show up on sonar, as even then, there'd still be that element of surprise since I almost always detect enemy boats way ahead of the sonar after seeing the lights on the horizon. I think it'd all just come down to their visual profile. Hopefully that makes sense.

The problem with adding submarines.... is that you then need to add effective countermeasures and it would add a lot more workload to the game.

You would also predominately die if you didnt have AWACS or the ability to drop sonor buoy's. This is why carriers in real life do not travel alone. Whilst carriers obviously have " some " methods of detecting enemy subs, they are very, VERY, susceptable to submarine attack.

If you think about it, you would almost always have to be scanning the sonor screen, especially in single player. The 10-15 minutes it takes to set up an attack on an island would definitely put you at risk of a sneaky sub attack. You would also be more likely to detect enemy torpedo's ( depending on when the homing becomes active ) before you detected where the actual submarine was.

With the game in its current state, having submarines involved would be just about overpowered as your likelyhood of finding them is less than 10% ( depending on enemy AI scripts, of course )

I would rather the focus be on bringing the existing game to its full potential rather than trying to bolt on some new half-baked thing.