Elysium was a name applied to possibly two places -- or one. One account refers to Elysium as a location where people could swim with the Obi-Amphibians (NA: Sky Pirates!) and another account refers to Elysium as being a lost Earth colony with at least one ocean. (NA: Parasite)
The latter account also refers to the Elysium system as being a "lost colony of distant Earth" and the site of the Artifact. (NA: Parasite)
- It is possible that, whether or not these are the same Elysium, that the Gates of Elysium existed on or in proximity to the aforementioned places. (DW: The Stolen Earth)