Find Karnitol's Satchel and return it to Kreldig Ungor in Desolace.
Well, we might not be without hope quite yet.
Along that same coast, but to the north near Ranazjar Isle, there're night elf ruins at the bottom of the ocean. A tribe of naga, the Slitherblade, make that their home. I think that'd be our best bet.
If a scouting party went that far south, then they must've been pretty powerful. If you're gonna find Karnitol's belongings, I'd start with the more powerful naga: the tidehunters or sea witches.