The planet of Selonia is among one of the Five Brothers of habitable planets in the Corellian system and home to the humanoid Selonian species. A mild planet, Selonia is best known for its vast oceans and the seafaring spirit. Landmasses on this planet resemble more of archipelagoes then large continents, and most of the islands are inhabited, mostly by Selonians but the planet also hosts a large number of humans of Corellian descent.

The Selonian species are a humanoid species that are tall and typically quick and agile. Selonians are dark-skinned, but their skins are covered by a short, sleek fur that gives them a seal-like appearance. Many evolutionary biologists trace their ancestry to amphibian creatures, perhaps like the seal, that roamed the oceans and beaches of Selonia billions of years ago. Their long tails that aid them in underwater movements especially give support for the evolutionary theory. A Selonian household unit is called a burrow or a sept, depending on the dialect, though sept is the more commonly accepted term. A sept typically consists of the male as the head of the household, who is accompanied by one female and any number of children and female servants they may have. The Selonian population is overwhelmingly female, though most Selonian females are not fertile. As nature would work itself out, the number of fertile females approximate matches the number of fertile males. Infertile females are often employed as caretakers of the young children or everyday servants. Infertile females do not enjoy a high social status in the Selonian society. The Selonian governments are called dens and are consisted of the elder fertile females. The Selonian nature is kind and generous, though they typically do not welcome prolonged diplomatic relationships with outsiders, particularly Corellians, as the outside cultures possess many characteristics that Selonians regard as corrupt to their culture. Most Selonians enjoy peaceful lives as fishermen, and they tend not to care about political issues that are beyond the Corellian System.

Ancient Selonian mythology tells a story of large sea monsters that live in the many oceans of Selonia. Because of the extreme depth of the ocean beds, this mythology actually was not debunked until fairly recent history when space flight was introduced to the Selonian people. From space, starships performed sensor scans and proved that there were no life forms larger than whales. Perhaps, one anthropologist hypothesized, that early Selonian seafarers were preyed upon by the whales, and the whales were actually the sea monsters of these ancient myths.

Because of the Selonians are known for their seafaring feats, many spaceships with Corellian origins are named after this watery world.