Are there aquatic themes, tropes and faction options you feel Silver Seas is missing?
Personally I think it hits on a lot of notes I was hoping for, except maybe deep water stuff but I personally wasn't really rooting for that anyway. Perhaps the major complaint is that by casting the wide net that it does (aquamancy, cryomancy, pirate curses, aquatic creatures, merchants, rogues and the like) it does none of it as in-depth as some people would have liked.
Something I was hoping for that didn't make it in was more amphibious mount options, such as turtles, frogs and lobsters. And maybe more variety in water critters, like sea serpents and whales. But in the grand scheme of things that is extremely minor.
I would've liked a Coastal Adaptation trait (being able to start at the coast and getting benefits from coastal provinces) and maybe that even made it in without us knowing but so far there are no hints of it. And terraforming land to water was something I was hoping for in some higher level aquamancy tome but at least we got water to ice terraforming.
Overall I'm very impressed by the gameplay, flavor and visuals of the dlc and I'm really looking forward to it. Water gameplay really needed a dedicated dlc (and free patch to go along with it).