Undermine isn’t an island, it’s an underground/sea continent under an island.Customisable ships that we can sail to various islands on. We can choose our crew, the style of the ship, it’s function and how we outfit it. In between the islands are naval combat with other ships, sea monster attacks, pirate raids, SEA SHANTIES, randomised islands to explore.
As for the levelling zones and capital city then Tel’Abim, Hiji, Ogrezonia, Undermine, Darkspear Isles and Plunder Isle. Zul’Dare is closer to Kul Tiras but it could be patch content and we sail to it for whatever reason. Booty Bay and Gadgetztan could also be expanded.
- - - Updated - - -
We have only ever explored one island in the South Seas and that is Zandalar. So no, most of it hasn’t been done. There are plenty South Seas islands in the lore, so no, they wouldn’t have to make up places.