51,000 light years from the core, Utapau orbited a single sun and was itself orbited by nine moons. It was composed of a small molten metallic core, with a rocky mantle and rocky, calcareous crust. Surface water made up only 0.9% of the planet, although most significantly, a vast subterranean ocean encircled the planet below the crust. Although extensive surface oceans once covered the planet, they leaked away to the subterranean ocean through the readily eroded crust through vast caverns that were once giant magma chambers. In turn, the erosive sea has contributed to the giant sinkholes throughout its windswept and grassy habitable areas. The resulting vast mineral deposits below the ocean are a great source of wealth for the planet.
Sinkholes on Utapau were a common geological feature that appeared in areas where the rock below the surface of the land is made from substances like salt beds, limestone, carbonate rock (which is referred to as a karst landscape) that can be dissolved by ground water flowing through them. This rock can also be weakened by acidic rain. When these rocks dissolve, large spaces develop underneath until it gets too big and the land above the gap collapses. Naturally-occurring sinkholes are also created by long periods of drought, or when caves with underground streams naturally give way
Utapau was a peaceful world that attempted to remain neutral in times of galactic conflict. The sinkhole world was shared by two symbiotic near-Human races whose common ancestors settled the planet at some point after 57,000 BBY. The languid, gray-skinned Pau'ans composed only thirty percent of the planetary population but served as the port masters, bureaucrats, and patricians of the world. The stubby, humble Utai composed the Utapaun labor class, which maintained the windmills of their sinkhole cities and served as handlers for the native varactyl and dactillion dragonmounts.
Originally, the Pau'ans and the Utai colonists lived separate lives; the Pau'ans on the unremarkable surface, the Utai deep underground. In the 10,000-year span before the Clone Wars, the planet's climate began to change, causing stronger and stronger hyperwind storms. This forced the Pau'ans to move underground, re-establishing relations with the Utai people and adding their own, unique touch to the Utai cities. The sinkhole communities soon became a mix of Pau'an and Utai architecture, such as the form known as Ossic.These cities were built into the crevasses and rocky ledges that lined the edges of the sinkholes.
The mixed population of Utai and Pau'ans were divided into city states, with occasional border skirmishes and small wars occurring between separate sinkhole communities.However, thanks to the efforts of Utapaun nobles such as Timon Medon the various cities were brought together and Utapau was unified.To fuel the modest energy needs of the sinkhole cities, many large windmill farms were erected on the wind-blasted surface. These farms were responsible for generating over 99% of the energy consumed by the Utapaun communities.
The massive sinkhole settlement of Pau City.
During the Great Galactic War, Utapau became one of the many battlegrounds between the Galactic Republic and the resurgent Sith Empire.Around 50 BBY, an offworld water-mining company discovered supposed healing elements in the underground water lakes of Utapau; the export of this water brought Utapau into the galactic community. For millennia, a rumor had persisted that the planet was one of the birthplaces of the Jedi Order.This legend added to the sales pitch, but the water was soon discovered to have no extraordinary powers and the business ended.In the time before the Clone Wars, the planet also served as the headquarters of Buuper Torsckil Abbey Devices