Ok, so I've searched this site for some while now and I couldn't find anything about this. It's possible that there might be something like it but not in Azjol Nerub.
Anyway, you need a Death Knight and a some partymembers.
When you have done the second boss in Azjol Nerub there is a road leading you further down in the instance. If you follow that road you will come to a big hole in the ground that you need to jump down in. Right before you and your partymembers jump down there, use the spell "Path of Frost" (Path of Frost - Spell - World of Warcraft). Remove your own buff in the air and you will survive, but your friends will hit the water as if it would have been normal ground!
Have Fun.