[ She doesn't seem terribly excited about the prospect. Thor considers this - it feels as if he's missing something, but he has no idea what. ]

It isn't complicated. [ He starts back into the water while she prepares. He thinks it unlikely that she'll be in any danger; it's just easier to teach by demonstration. ] Think of it as you would any exercise or technique. It takes time to become proficient - but unlike combat, you need not worry about mastering it.