Start from Titan's Staircase Waypoint
Make your way to Fisher Leudap
Swim down and you will come to this
Press "F" to play the pipe organ and you will see the controls to it
Now play it in this sequence
Code:
2, 3, 4, 5, 4, 3, 2, 2, 3, 1, 1, 2, 8, 6
And with that VOILA you haz opened chest and as with the other "instance" exploits log out from where you are and relog in to do it over and over again. Got me 6 greens, a handful of rares and pearls etc. Pretty good drops!
Enjoy!
Edit: hehe spare a rep if you would for the nice peekturesss! :3