Sub surprise strike and submerge sequence

[RYNO87]

Only 2 subs are in combat with no destroyers. The defending sub chooses to submerge but the attacking sub uses surprise strike. If the attacking sub gets a hit but the defender submerged, does that attacking hit count or miss bc of the defenders submerge ability?

[Witt]

@RYNO87 good day.
The attacking Sub can’t attack the defending Sub, if the defender decides to submerge. It is safe and alive.
Only a Destroyer prevents this.