It's an RPG and there are many places but you'll still have to explore a lot and get reasonably far into the game before you uncover 150.
Even if you have removed the "fog" from parts of the map, some locations can still be found by exploring those areas. You can also access a bunch of new locations in the Bitterblack Island DLC. Lastly, a few areas are blocked from your character until you progress the story far enough (e.g., the Duke's Manse, The Tainted Mountain, etc.) that will contain a few new locations to discover.
If you're diligent in your exploration, this will come almost as part of the story. I played the game through maybe half a dozen times and tried uncovering everything and ended up discovering 199 locations.