So how many "Discover-able" Locations are there in game?

So I thought I'd found all the locations after using a map to check. I also added map markers to see if there was any I missed but I reloaded after doing so cause I know it can cause glitches with the locations found stat. 315 is what I had after discovering my last location. However I wanted to check a different stat and I see this number's gone up to 318, but I never discovered anywhere new. Are there some unmarked locations that count to this stat? Does clearing locations count as another location. I'm so confused and if anyone knows what's actually going on with locations it'd be much appreciated.