Under the world tree in hyjal, swim all the way down. Use unstuck once you have "lodged" yourself inside the rocks that permit you from going down any further (make sure Hearthstone is on cooldown or destroyed). You will be unstucked below the rocks. It goes down just a little bit further, but i thought it was pretty cool not really any point to this, but I feel mmowned should know everything i do
*to get out, you can simply swim upward through the rocks