Planet Threa is the homeworld of the Retha. It is a pleasant, watery planet with plenty of fertile ground and varied environments. It is also resource-rich, with mild seasonal changes and no large predators. The planet is small, about 1.5 times larger than Mars, and has an atmosphere of 24% oxygen, 70% nitrogen and small amounts of other gases, like carbon dioxide and argon. This atmosphere allows for the dual-air-breathing Retha to thrive.
Despite being the Rethan homeworld, much of Threa is untouched, covered in various tree-filled environments. Both poles are permanently frozen, with the ice pulling back every summer. Weather is varied throughout the year, with wet storms across most of the planet in the winter, mild, windy but sunny ‘Spring’ months, hot, humid summer months and a cool, dry period just before the winter storms start once more.
While a third of the non-water-covered surface is covered in trees, the rest is equally split between large, flat plains and mountain ranges, although most mountain ranges are considerably small compared to other planets, with no mountain being taller than 6000m tall.
The plains of Threa are where the Rethans have built their cities, building them on and around old Threavok religious sites. Rethan agriculture uses a farrow system, rotating their crops with every new plantation and leaving fields with nothing in them for a year to ensure that nutrients return to the soil.
As well as natural resources on the surface, Threa has a huge amount of underground resources, which are carefully extracted by publicly owned Rethan mining companies throughout the year, on bi-weekly shifts. The most important of these resources are access to the vast, deep cavern systems of Thre-Sia, which give access to super-conducting metals, as well as large quantities of diamonds and other carbon-based minerals.
Wildlife is mostly small on Threa, as the largest predators had always been Panvok beings, many of which disappeared when early Rethavok began to adapt and thrive. Apart from Rethans, there are minuscule populations of Varga and lower-level Thanatians, as well as large, cat-like Pantzeras, a low-level Panvok species that mainly lives in jungles.
The oceans of Threa are mostly huge, deep abysses, only getting shallower near land. The deepest point is the Kenon, a trench that reaches 17km at its lowest points. Life is varied in the ocean, consisting mainly of heavily armoured invertebrates on the ocean floor, swarms of bony fish at higher levels and large, armoured mammal creatures and shark-like beings as main predators. Coral and seaweed reefs are very common among the edge of the oceans but rare elsewhere. Plankton is common all over the ocean, down to depths of 300m. After 300m, most of the ocean is incredibly dark, with insufficient sunlight for plants to survive. The majority of beings in the sea sieve the water for food.
Each city has a distinct job. Thre-Avstra is a farming city, Thre-Sia is a mining city, Thre-Etas is a manufacture and processing city, Thre-Sypria is a military city and training facility for all Retha, Thre-Nera is a large fishing and hydro-power city and Thre-Vretantia covers most other jobs, particularly power supply, as well as being home to the political and judicial systems of the Retha.