Elysia is a large planet covered by a perpetual cloud of unknown gases, possibly a gas giant. It had once been inhabited by the Chozo, who had constructed a floating interstellar observatory, SkyTown, in the skies above the planet.
Since the planet is covered by a layer of clouds with no discernible surface beneath, it is likely that Elysia is a gas giant. Elysia has very few native lifeforms, such as the Sky Puffers that feed on the planet's toxic gases. At one point, a Phazon Leviathan had impacted upon the planet's core and threatened to spread the taint of Phazon Corruption. However, thanks to Samus Aran, the Leviathan was destroyed, halting the spread of Phazon on Elysia.
Elysia's only settlement is a floating interstellar observatory built by the Chozo, known as SkyTown. The facility is inhabited by the Elysians, sentient mechanoids created by the Chozo to aid in maintaining SkyTown, as well as a variety of security and repair robots. SkyTown's observatory uses observation satellites that are launched towards distant worlds, allowing the facility to study them from afar. Currently, SkyTown is operated in partnership between the Elysians and the Galactic Federation, and is administrated by Aurora Unit 217.