Well, there are a lot of positive posts here about the U-boat addon. My experience with it tells me you want to use it with mods. The reason is that the stock addon doesn't have good missions and campaign game.
I took my first boat all the way to Tokyo, expecting to encounter something...didn't.
There were no planned missions after that one...just go hunting.
I was disapointed too with the port of Singapore. They represented it like a jungle village with straw huts. This was a major city & port.
The mods, once again, will take UBI where it should have gone.
