After defeating Dr. Eggman and his assistant, Dr. Julian Snively, at their base on South Island, Sonic the Hedgehog chased the two mad doctors down to Westside Island, where he teamed up with his new sidekick and best buddy Miles "Tails" Prower as well as the Knothole Freedom Fighters. They arrived in Aquatic Ruin Zone after passing through Chemical Plant Zone in their efforts to defeat the mad doctors, whose goal on Westside Island was major construction and refinements as part of their plan for world domination. From here, they chased them down to Casino Night Zone. (VG: StH2, SSD: #12)
- Aquatic Ruin Zone may or may not exist, as it was never shown or mentioned in the comics, but was a zone within the video game, Sonic the Hedgehog 2, which was confirmed in editor notes in the comics to be canon. Therefore, it is considered tier 2 canon by this site's canon policy, as it does not contradict already established canon from tier 1.