well thats just stupid and COMPLETELY threw me off as to where Morrowind really was! I thought it was an island far off from the rest of the world as it was in the game but that map shows it being a 1 hour swim away from the land...
That's because they didn't attempt creating the mainland part. The first plan was to do the whole province, but they thought it'd be too much work and decided then just to do the island, allowing them to do the "infinite sea" thing all around.
The slowly-progressing Tamriel Rebuilt mod for Morrowind is creating the whole mainland part of Morrowind (but not the whole continent, we're not crazy enough for that), starting from the north-east. Currently, map 1 (said northeast) is available in beta version. See my sig for more infos.