The Deadmines (VC or DM) are located in Moonbrook, Westfall. The closest flight path is Sentinel Hill, Westfall (Alliance) or Grom’Gol Base Camp, STV (Horde). Watch this video to see the fastest route.
Once you enter the mines, always go right.
0:00 Sentinel Hill
1:17 Deadmines Outer Entrance (Moonbrook)
2:28 Instance Portal