The Zangar Sea is an area introduced in Warlords of Draenor. It is located to the North of Shattrath City, between Frostfire Ridge and Nagrand. This area contains natural features and flora in common with the Zangarmarsh area of Outland (they are located in the same location after all), but currently contains no quest hubs, flight paths or NPCs, only mobs.
Possible Future Zone Edit
The extensive underwater features suggest the Zangar Sea could eventually become an underwater questing area like Vash'jir, though it is highly unlikely.