Is there a fix to stop the crew from being underwater in Sayda Neen? There where two that were already drowned.

That's so weird. You could load the mod in the CS and bestow a Water Breathing ability upon them.

Do NPCs use Water Breathing potions when underwater?

Thats odd. Aside from potions, and if you have magic ability, just make a spell that gives really long water breathing to others. I once made a spell that gave someone I was with like 6 minutes of water walking.(yes you read that right, may have been 3 minutes) I also made a spell that gave me 6 minutes of water breathing. No I didnt cheat to make these.

You mean you don't get this issue at all?