"Pandora's Quadrangle" is the name given to an unspecified region in the Atlantic Ocean. Dib describes it as the stormiest place on the whole ocean, and states that numerous aircraft and boats have disappeared in it over the years. He apparently personally has multiple theories as to what's the cause of this, including ocean yetis and space bugs.
When Dib and Zim both pick up an Irken distress signal emanating from the Quadrangle, they both fly off to investigate it. Arriving at the source of the signal, they discover a large tear in reality surrounded by intense weather. This tear causes the Voot Runner and Tak's Ship to malfunction, before sucking them in and depositing them on a small planet surrounded by other portals.
It is later revealed that those other portals all lead to the Pandora's Quadrangles of numerous other alternate universes, and that the Zims of those universes have each likewise followed the signal and gotten stranded. They have since established a society, based on a numbered hierarchy amongst themselves.
In Issue 49, it's revealed that the Quadrangle portals were created when an alternate Dib (dubbed "Zib" by GIR due to having a PAK on his head that makes him similar to Zim) accidentally destroyed his universe in the process of trying to destroy the Irken Empire, leaving just the small portion of Earth surrounding his castle and tearing open the portals. Zib then created the distress signal to lure in the Zims so that he could enslave them, eventually brainwashing the strongest ones so that he can use them to spread a virus to the Irken Armadas of other timelines and destroy them.
Before he can do this, however, our Zim uses his weapon and the portals to alter the timelines and send everyone back to their own realities, closing the portals in the process. He and Dib are then left floating in the ocean where the portal used to be.
Facts of Doom
- Pandora's Quadrangle is clearly a parody of the Bermuda Triangle, an ill-defined section of the real world Atlantic Ocean where ships and planes are said to have disappeared under mysterious circumstances.