Oris is about 95% ocean, with only two ice caps breaking the surface at the poles. While the water planet seemed more like a curiosity than anything else, it was soon colonized by a group of religious outcasts that sought refuge away from the oppressive monarchy of Laro Prime. They adapted Mon Cal technology to create a city below the water, Ceray.
The population of Oris would soon grow as people discovered that the planet was a great location to hide out in for those who didn’t want to be found. The largest influx came when the Empire designated the Laro system as their newest outpost. Other underwater cities other than Ceray were constructed but the exact number is unknown.
Early on in the planet’s history, the Human colonists soon discovered that the water world was already populated with a native species. Officially known as Orisians, they soon became colloquially known as "Shellbacks."
When the notably shady colonists first encountered the Shellbacks, it was actually the natives who proposed, in passable Basic no less, of creating a coalition between them and all the Human cities on Oris. The leaders of the major cities, impressed with the highly intelligent natives, not to mention the Shellback’s abilities to communicate with the sea life of Oris (the huge city-sized predators included), readily agreed to the deal.
Since that time, Oris has prospered as the two races have benefited from the other. The Shellbacks have access to the advanced technology of the colonists and the Humans have learned all about Oris and how best to survive on the planet. Despite the apparent advantage that the Shellbacks seem to have over the colonists, the natives have made no move to take control, merely content to have the two races coincide as equals. In addition, only a few of the Shellbacks have made it off planet to the other two worlds.