Hey!
The old deadmine secret. It was accessible with wall-jumping and/or a mage-blink bug. This was fixed a long time ago.
But there is a different way to get there, without using "additional" programs or model editing.
What you need:
1. Any sort of slowfall - but at least 15 seconds.
2. Rocket Boots (Rocket Boots Xtreme - Item - World of Warcraft).
How you do it:
Just watch the video which i have made. It should be self-explanatory.
You can download it HERE!
(I don't care if you can read my name)
1.) First you have to climb up that cave.
2.) Then use the auto-unstuck function - be sure that you have cooldown on your hearthstone (or delete it).
3.) Stand at the same position as me in the video. Otherwise you will die.
4.) Use the Rocketboots and then slowfall - as fast as possible.
5.) Done - now just swim to the deadmine secret.
Screenshot:
Well... hmm... i forgot it.
But here is a screenshot which i found on google:
http://img150.imageshack.us/img150/8246/dm2vr2.jpg