If you dont want to read all the text, just look at the video on the bottom of this post.
To get the "Going Down" achievement, you need to survive a 65 yards fall.
Problems:
* If water dampens your fall, it wont count
* Levitate also disqualifies the fall (not sure about the mage's slow fall though
However:
* If you're paladin, though, the bubble DOES work.
* If you're a druid, flying really high and going back into flight form when you get the achievement before you hit the ground is supposed to work.
* If you're a rogue, you probably wont have a problem either, due to the decreased falling damage.
For the rest of you, though, falling 64 yards wont get you the achievement, and if you fall 70 yards, you die.
What's required:
1) Getting to Shattrath
2) Making sure your hp is 100% (doesn't matter how much your stamina is. if it's not 100%, you'll die. If it is 100% you wont die even if you've got 10hp total)
Get to the scryer lift, go up and when it stopped at the top, jump down again, aiming for the lower floor.
Was going to record my own video, but I found someone else had already
[ame="http://www.youtube.com/watch?v=KAoQbXWlEuk"]Going Down[/ame]