Hey I found out, that when you have that daily quest from that gnome,
Frazzle Geargrinder Frazzle Geargrinder - NPC - World of Warcraft
where you can use the Jump-O-Bot you can jump through the mountains! (Through the ground) I Will make some pics how it works:
First: The Map. Where it is for the alliance (works for horde too, but don't know where it is):
OK, second Img, use the Bot:
Now get there were I stand in the third image:
If you are there, use the Spell, bind on the third Hotkey (3). Target there where I am targeting in the fourth image:
Now you will jump through the mountain.
Immidiatly after you activated that spell, leave the Bot with the Red arrow on the right side. Now you will fall through the ground and you have to use your flightform:
Now you are under Northrend and can fly (Alive) everywhere! Gratz
PS: Don't be sad if it doesn't work the first time