Now that we know we'll be able to gather underwater (Sonic-style countdown, GO!), I'd be curious to know what recipes SE might have in mind to justify this new twist on DoH classes.

Personally, the first thing that came to mind upon hearing this is sushi. What grows at the bottom of the sea? Seaweed. What's seaweed generally used to make? Sushi. I can't be certain which varieties will be given or what stats SE would have in mind, but is seems like an idea that is a long time in coming.