The 1984 campaign in Cold Waters is brutal. You start with a dated Sturgeon-class sub, and losing a single mission sets the NATO fleet back weeks. Here is how the trainer improves the experience:
Sometimes, after a 12-hour workday, you don't want to spend 45 minutes slowly crawling under the thermal layer to avoid a sonobuoy. You want to surface, launch cruise missiles at a Kirov battlecruiser, and laugh. The trainer facilitates that arcade experience. Cold Waters 1.15g Trainer
Assuming you have found a legitimate trainer for version 1.15g (often named CW_1.15g_Plus12_TR.exe), follow this protocol: The 1984 campaign in Cold Waters is brutal