South Island (サウスアイランド, Sausu Airando?) is a location in the Sonic the Hedgehog universe. It is the home of Sonic the Hedgehog and Miles "Tails" Prower, and is the main setting of the duo's earlier adventures. South Island is known to be a trove of gems and ancient ruins, that supposedly shifts along the water due to some connection to the Chaos Emeralds. Flickies also inhabit the island.
South Island consists of many Zones.
- Green Hill Zone, a large grassy plain with lakes and waterfalls.
- Marble Zone, ancient ruins half-sunk in lava.
- Spring Yard Zone, an urban area with pinball bumpers and springs.
- Labyrinth Zone, an underwater maze.
- Star Light Zone, a peaceful, high-way city area that, at night, sparkles like the night-time sky.
- Formerly, Scrap Brain Zone, a heavily industrialized area that served as Doctor Robotnik's base of operations on the island. Some parts were salvaged from here to create the first Tornado biplane.
- Bridge Zone, a long bridge over a river.
- Jungle Zone, a rain forest with wild rivers and vines.
- Underground Zone, a volcanic mountain, once used as a mine.
- Sky High Zone, the top of a mountain that reaches the clouds.
- Aqua Lake Zone, a lake surrounded by fountains and pillars.
- Turquoise Hill Zone, a grassy hillside area, much like Green Hill Zone.
- Gigalopolis Zone, a sprawling urban area with varying passages.
- Aqua Planet Zone, a group of ruins partially submerged in water. Despite the name, there is actually very little water.