The New Jersey Parallelogram was an interdimensional portal that occurred in the episode Venkman's Ghost Repellers of The Real Ghostbusters. Peter's father was trapped in there after he tried to help the Ghostbusters rescue a ship crew that got stuck there after believing that his "Ghost Repellers" actually worked.
The earliest known incident attributed to the New Jersey Parallelogram is the disappearance of the Battleship Bismarck in 1941. Since 1980, the New Jersey Parallelogram existed just west of Ambrose Light, a light station at the convergence of several major shipping lanes in Lower New York Bay. Seven known ships disappeared due to the Parallelogram and the area became infamous for extreme psychic turbulence and cross rip convergence. In theory, it contained enough psychic energy to raise Atlantis.
In the mid-1980s, Jim Venkman sold "Ghost Repellers," a fake anti-ghost product, to a liner set to explore the Parallelogram. This inevitably brought the Ghostbusters into the investigation, to avoid legal ramifications. They eventually converged on the Parallelogram's energy gate and were teleported inside. The P.K.E. Meter was set to detect reality by reversing its polarity and the team towed the liner to safety outside of the Parallelogram. However, they had to go back for Jim Venkman. They found him in a dome being terrorized by ghosts. Upon firing on the ghosts, the structure of the dome was weakened. The Ghostbusters and Venkman were able to safely escape. Everyone witnessed the Parallelogram collapse into the ocean and the surrounding weather mass stabilized immediately.
Egon Spengler explained that everything in the Parallelogram was supernatural. The Laws of Physics had basically been taken and crumpled up like paper. Nothing follows the same conventional Laws of Physics. Egon, also when finding the lost ship, had both ships tied together, because then they would share similar laws then. Gravity was not shared by objects in there as Jim Venkman's ship passed by the lost ship upside down. The Parallelogram, it would seem, was very unstable, however, as the Ghostbusters shooting the Parallelogram Ghosts caused it to crack up.
- The New Jersey Parallelogram is possibly a parody of the Bermuda Triangle urban legend, as both are behind the mysterious disappearance of various planes and ships. In the beginning of the episode, it is described as "like a small, nasty version of the Bermuda Triangle."