688(I) Hunter/Killer with the Jane's manual is great too. I find it more immersive than Cold Waters as you are in charge of the waterfall and have to move the cursor like a true sonarman to find the good signature.
If you liked 688(I), I strongly recommend giving Dangerous Waters a shot. It’s a sequel made by the company, featuring submarines as well as surface and helicopter platforms, and is currently on sale.
https://store.steampowered.com/app/1600/Dangerous_Waters/