You can take a boat from the northern dock of Auberdine to Rut'theran Village. From Stormwind, go to Stormwind Harbor, then take a boat (on left) to Darnassus. Find flight master and fly to Darkshore. From Theramore Isle, swim north along the coast, then go west (safer than going through Dustwallow Marsh).
Hereof, how do you get to darkshore from darnassus?
You take the portal (in Darnassus) and it takes you to Ruth'eran Village. From there you wait for the boat on the dock. There's also a flight path from Rut'theran Village to Auberdine, for the record. If I recall, for your first visit, you need to actually take the boat, then get the flight point.
Which boat goes to Stormwind from Rutheran village?
Rut'theran Village. Rut'theran Village is an outpost port for the night elf city of Darnassus, located at the very bottom of the great tree Teldrassil. There is a portal here that goes directly into Darnassus, as well as three docks with regular boats going to the Exodar and Stormwind City.
How do I get from exodar to Stormwind?
Ummm, I would recommend going to the Exodar first. It's the Draenei home "city" on Azuremyst Isle with an AH, bank, trainers, etc. There is a boat just outside of the Exodar that will take you to Auberdine and onward. No need to swim, and no need to go all the way to Stormwind at this point.