I live in Sweden, at North 59 degrees. I´ve been traveling around my country to seek for the darkest places to observe the nightsky.
I´ve been in bortle 1,5 as the darkest place, in December when it is at darkest here ( Dark Grey on LP map).
But When my eyes has get used to the dark, the sky is still Dark blue, not black. I can with ease see trees, and stuffs around me on a great distance, and the milky way has about the same structure/brightness as in the Yellow/green zones.
Could it be that the sky is much darker in the southern hemisphere than the north, at bortle 1?