The sub gets it’s sneak attack (step 2) on every cycle of combat (steps 2-6).
Please ask if anything remains unclear.
HTH 
Particularly that. What is a sneak attack? It’s combat before the combat phase. Could you explain that to me as well? I’m a tad confused there.
@P@nther:
I think I got the jist of most of the Sub. Planes can’t hit the sub unless there’s a destroyer present.
Welcome to the forum, Miffinator!
This is not correct for the Revised Edition. Please verify to which version of the game your questions apply.
Again I’m using the 2004 Revised version. I’m confused about the Subs. What benefit does submerged do?
Few quick questions on Subs
•What’s the purpose of Sneak attacks.
For example if I send 1 Sub vs 1 Carrier can the Sub sink the Carrier on a hit of 2 or less without having the carrier retaliate? Does this also apply if there’s fighters on board? Is that how that works? Furthermore does it only work once per combat round? So at the start of the combat round the Sub only gets 1 Sneak attack then it operates as a normal combat unit?
•Can other Naval units attack subs?
Can I send a battleship after a Sub or can only Destroyers do that? Or do Destroyers only minimize the Sub’s ability to flee?
I think I got the jist of most of the Sub. Planes can’t hit the sub unless there’s a destroyer present.