Everybody I knew used to not bother with the key -- You could just hop into the pool and swim diagonally down into the crack of the stone doorway, then keep ducking/standing and you'll swim right past, glitching your way through the door. Large toons had to shrink to do it. Nowadays it's just unlocked and you can click to open, or you can jump right in from above.
Edited, May 4th 2012 11:17am by Gazic