ONE PIECE ep. 523 // ch. 603 || Luffy & Zoro really wanting to catch some fish while underwater on their way to Fishman Island
"As you can imagine, when there are too many holes at once, the bubble will break. For example, if we are bitten by a Sea King's fangs, it'll be trouble.
So we have to be careful with creatures and obstacles in the sea. As long as we don't do anything foolish from inside, it’ll be fine."