I like the idea. However I'm having difficulty trying to figure out how the map layout would be. Most of the lore in the game has the fighting centered in Cryodiil, any fighting outside are small espionage/skrimishes in the PvE territories with Pirate/skirmishing naval battles, nothing really large scale.
Another issue is how the mechanics will work. Will multiple players controll one ship, or will each player get a ship on their own. This can be a very huge problem because many players almost refuse to work togeather to operate a single ship. And single crewed ships could just lead to the usually problems in PvP such as zergs, AP farming, ect...
For some new pvp content/map the three alliances could fight in a naval battle.
Capturing/sinking ships with siege.
I thought this would be a good change of pace for eso. Through out TES lore there are references to fleets sea battles so having pvp take place on a sea battle wouldnt be absurd.
The problem I have with this idea is that the layout might end up like cyrodiil with a un accesible central point with all sides fighting from two directions. It would be cool if the layout was dynamic and the faction fleet position changed or something.
Just an idea c: