Go to the aquarium room (the room that contains the painting that leads to Jolly Rodger Bay). Go up to the glass panel to the immediate left of the painting (the glitch works on both sides, but for the sake of direction use this window). Go to the left edge of this window, where it touches the wall. Walk into this area and you should see that when you walk into it, it bumps Mario around. Now you need to turn Mario around so that he faces away from this seam. Start doing backwards longjumps at it. To do this, do the longjump forward and then hold back the control stick and repeatedly hit the jump button. You may need to adjust your angle several times as it needs to be very specific. You'll know you've got the angle right if you start doing multiple jumps when you hit the ground. If you can get Mario to do multiple jumps, keep on jumping and Mario will hopefully pick up enough speed to pop through the window (similar to stair glitch on the previous page). Once you get in there, you'll see that there isn't actually any water in there, so you can just run around on the floor and look at the pretty fish. Also you'll notice that there is no way out of the aquarium, so you'll need to reset.
Submitted by: Dom Dunc