South Island (Classic Sonic's world)

South Island (サウスアイランド) is a location in the Sonic the Hedgehog series. It is an alternate version of South Island from an another dimension set in the recent past.

Past
South Island's early history was most likely largely the same as its mainstream counterpart's up until at least some time after the West Side Island incident.

Sonic Generations
In Sonic Generations, Sonic paid a visit to South Island's Green Hill Zone. While there, the Time Eater would appear and sent Sonic to the White Space.

After the Time Eater had been taken care off, Sonic and Tails returned to South Island's Green Hill Zone through a Time Hole left behind by the Time Eater.

Sonic Mania
In Sonic Mania, Sonic, Tails, Knuckles and the Hard Boiled Heavies got transported to South Island's Green Hill Zone after the Hard Boiled Heavies unearthed the Phantom Ruby. Having gained free will and updates forms during the transportation process, the Hard Boiled Heavies fled with the Phantom Ruby, prompting Sonic and co, to go after them. Along the way, the heroic trio got ambushed by Dr. Eggman and his Death Egg Robot. After being defeated by Sonic and co. though, Eggman managed to forcefully obtain the Phantom Ruby from the Hard Boiled Heavies, which he used to sent Sonic, Tails and Knuckles to Chemical Plant Zone.