Distances roughly north-south, to noticeboards are 2259 paces and 1674 paces from "Hanging Tree".
This is around what I estimated as the probable "internal" active part of the map, at around 4-5km... which is also around the acknowledged (playable) size of Skellige.
There is additional high res terrain ~ some of which is obviously playable (there are buildings which look to be intended to be visited) a little beyond the location of known notice board locations, but I haven't yet tested the 'edges' of the world... the 8.5km given in design documents is the whole high res map, not only the usable area. (Unless of course a pace is significantly over 1m).
Distances are almost always substantially longer because direct travel is risky (high level monsters) and often blocked, by water, cliffs or other obstacles. (Technically many can be crossed, but it is often faster to find a slightly longer route and use Roach).
From memory (I didn't remember to actually record values), White Orchard was only around 1km square, maybe a little more, so Velen and Novigrad are around 9-16x as large and the density and 'danger' of contacts is higher too. Not objectionably, but enough that some care needs to be taken while moving around.
Note "map edges" aren't straight. Bits stick out into the margin, and the margin sometimes creeps into the main area "Ameoba-like".
So far I'm only a little way into Velen on a restarted playthrough, and I've only just started taking quests from noticeboards (and picking off the low hanging fruit as I pass by).
I'll get to main quest stuff in a little while ~ I feel I rushed into it too fast last time and had some trouble with a few encounters.
then again I am also the type of person who may of spent two hours of in game time just watching a sunrise :innocent:
