>>57726724Cool boat is your home away from home. It's customizable, is an NPC and story hub, and has various amenities like a Pokemon center and mart. This means they don't need to sprinkle them around everywhere in static locations and frees up the region to be more rugged and undeveloped.
The sea is open-world, obviously. Sail around, find shit, do stuff. You can drop anchor wherever and hop over the side to surf around. Most islands don't have a port to dock at, at least not one big enough for your cool boat, so this is how you get to most of them.
Bigger, more developed islands you can actually dock at will frequently see some of your crew and/or gaggle of NPCs disembark and do stuff around the island. This is how most plot stuff happens.
There's also stuff under the sea, caves and sea-floor stuff and Atlantis-style ruins. The latter is plot important. There's mechanics to find them that I can't think of the specifics of in this spur-of-the-moment stream of consciousness.
You regularly engage in naval Pokemon combat with ships from Team Pirate. This differ from the usual stuff by having you need to keep maneuvering your cool boat around to avoid bigger attacks while still doing the usual turn-based stuff. Picture too ships circling eachother while Pokemon on the deck shooting long-range attacks at eachother. There's big-ass sea monster Pokemon too that operating in similar ways.