Board Thread:General Discussion/@comment-206.74.175.104-20151018163917/@comment-1600847-20160206220814

Blademaster Jauffre wrote: They blocked off the coastline of Hammerfell as well as the one from Cyrodiil. Tiber would still be able to launch ships from ports in High Rock, Skyrim, Morrowind, Black Marsh, Elsweyr, and Valenwood.

It's impossible that the Dominion could cover the entire coastline of Tamriel.