Found this by accident after our last SSC nostalgia run
So, first approach the SSC Waterfall in raid group so it disappears.
Then stop just before the portal so you won't get instanced and leave your group.
After that simply walk thru the portal, there is no invisible wall there for some reason.
Done!
This might have some use in PvP, actually I found it quite fun to harass people getting ready for raid outside.
Enjoy!
This could also have belonged to Exploration section, but because you can gain an advantage over other players with it I decided to post it over here