I have been here twice, on a troll and tauren. I don't know if it is possible to intentionally get here, but both times I fell through the world while in Stranglethorn Vale and ended up in the sea south of Silithus. The first time was in classic Wow, second in BC.
There was no fatigue, I could not drown, when I touched the sea's floor I instantly died, there was a spirit rezzer.. in the middle of the sky. And oh yeah, NPCs and random objects were raining from the sky then teleporting back up. They were killable if you could get them before the evade.