Tethys is a large planet in the Viperius Galaxy. Although much of the planet is covered in deep oceans, tropical islands dot the surface. The largest continent, Hyperion, is about half the size of Australia.
Tethys orbits the star Tiberius, a blue supergiant. This star keeps Tethys hot and humid. A recent study conducted by the Salsenes suggests that in a few million years, the planet will be drawn to close to its sun, becoming a Cthonian planet similar to Inferno.
The atmosphere of Tethys contains approximately 78.09% nitrogen, 20.95% oxygen, 0.93% argon, 0.039% carbon dioxide, and miniscule traces of other gasses.
87% of Tethys is covered in water, with the other 13% covered in small islands and one small continent.
Tethy is populated by a large variety of plants and animals. Tropical Fern Forests dominate every island. Vertebrates never evolved on Tethys; the world is dominated by invertebrates such as land-dwelling echinoderms called Flowerheads and oceanic crustaceans such as the Hammurabi. Annelids fill deep ocean ecological niches, and oxygen-breathing mollusks rule the forest canopies.
Not much is known of Tethys' distant past, as the primordial invertebrates left hardly any fossils.
In modern times, Tethys is colonised by sapient beings called Salsenes. Led by captain Sera Nestos, they successfully planted colonies on Hyperion and a few of the islands. Nestos is currently planning a submarine expedition to the depths of Tethys.