Copyright © HBO/Elastic
This “world map” is not precisely absolutely accurate, because as explained in the interview with Art of the Title, the map of Essos was in essence from a draft of the map by GRRM, done by hand, and it seems likely that some of the internal details are more approximation by Elastic than anything else. However…
Wow. This is our first, high-resolution look at this map of Westeros and Essos, and even if there’s some copy-and-pasting apparent (note the forest on Essos’s coast which almost exactly matches the Karstark’s forest in the North), it still gives a sense of both the scale and the rough coastal outline. Is the Sunset Sea really that narrow? That’s harder to say, as we don’t know that GRRM gave any sense of how far away one would be from the other.
Note that the continent to the north of Essos is not from GRRM, according to a statement from him when directly asked about it. He indicates that there’s only a few islands and a polar sea to the north.