After seeing the new adventure trailer, the background at the end of the video shows a Sunken Kingdom, and also, remembering what Belle said.
"Pirate courage alone is no longer enough, but true allies are hard to come by out here. The cost of their loyalty will be high. I think, perhaps...It's time for us to take a dive."
Could this adventure show the Merfolk being involved in the story? It might be the case judging by the way she spoke, so that could mean we'll see a Mermaid character appear.
Not only that, but it appears that the Servant of the Flame's spy was watching her, meaning Reaper phantoms will try and stop us from whatever it is she's looking for.
