User blog comment:Atvelonis/E3 2018 Coverage and TES VI Teaser/@comment-1600847-20180611203626

Some guy over on the TES subreddit did an interesting analysis of the geography we see in the trailer. Warning, it's LONG (and speculation, naturally)

https://www.reddit.com/r/ElderScrolls/comments/8q653e/elder_scrolls_vi_announced/e0gton6/

TL;DR, based on the position of the sun in relation to the coastline and the vegetation/lack thereof, what we see in the teaser is either the Northern coast of High Rock ,or the High Rock coast of the Iliac Bay (if what we're seeing is in Tamriel, if not it's anyone's guess). So High Rock is either the province TES VI will be in, or one of the provinces, if Bethesda goes for multiple provinces.