First contribution. On the Isle of Thunder there is a staircase and a door behind the God-Hulk Ramuk rare. Its locked and cannot be opened currently. But there is a glitch in the right door hinge that you can walk through the door. It works for my Mac Computer but according to my friends it wont work for them so just use a passenger mount to get them through it. Once you get into door the second door just lets you walk through it. You are now on the docks area and to your left is the Swollen Vault. Much like the Thunderforge this door is unlocked and you can go inside. There is a boss who will eventually drop a key to unlock the chest on the opposite side of the room. BUT, you can get the achievement for Platform Hero - Achievement - World of Warcraft
So in recap.
Go to the door down the staircase. Go up to the Right side hinge and strafe left and right while walking forward.
Go through both doors.
Your on the Dock which is just a ton of mobs and the Swollen Vault. Get achievement if you desire.