Submarines and stealth?

[u/Chrysocicada]

Playing the Pacific scenario. In the tooltip it says "In Battle, they are invisible until attacking or adjacent to enemy Units."

However, it seems that simply attacking from afar does not break stealth during battle. It also seems that revealed subs are sometimes able to regain their stealth after moving (maybe by entering deep water?)

How does stealth work in battles, exactly?

[u/PublicLlama]

You've essentially just described it.