[He doesn't want to admit that he's a little worried either, but, well, it shows on his face. Fighting in water is hard, and it could take some time getting used to it. He doesn't want anyone to get hurt while getting used to it, if it can be avoided.]

I don't want to get any non-fighters mixed up in this, but there must be a few people who have been around long enough that they're comfortable fighting underwater. I'd rather not have to find out firsthand how much those nanites can fix.