The Periterranean Sea is the oceanic water body that surrounds the Illuminatian continent and envelops much of the Neonisi planet. The Periterranean Sea forms the perimeter of Illuminatia on all sides of the imposing land mass.
The full extent of the Periterranean Sea is unknown and the vast majority of it is presumably unexplored by Illuminatians, as Illuminatian explorers have not yet engaged in conquests outside of the Illuminatian continent and its immediately-adjacent islands.
The tentacles of the Periterranean Sea that penetrate the perimeter of the Illuminatian continent are known to Illuminatians as a series of large bays. Four of these bays— Greater Amadeus Bay, Brookeview Bay, Randall Bay, and Symphonic Bay –etch the continent's four eastern peninsulas. The remaining major bays of the Periterranean Sea include the Anglo-Hungarian Bay in northern Illuminatia and Philharmonic Bay in southwestern Illuminatia.
Illuminatians gave a name the Periterranean Sea following the full exploration of the Illuminatian continent and following astronomical discoveries that established that Neonisi is a toroidally-shaped planet. The name communicates the spirit that the global ocean on Neonisi both surrounds the Illuminatian continent as well as envelops the bounds of the toroid of Neonisi from all sides. A modest level of poeticism was involved in the giving of the Illuminatians' name to the Periterranean Sea.