Underzone is a location that appears in the Sonic the Comic series published by Fleetway Editions. It is a Zone of Mobius, located directly underneath the Emerald Hill Zone. Entirely populated by a kingdom of worms and led by a queen, it is a well-kept secret from the rest of the planet.
The Underzone consists entirely of a subterranean tunnel network deep underground. The majority of the worms that live there are seen at work as coal miners, using the natural materials for fuel and everyday objects. Their food of choice is Mouldcake.
Miles "Tails" Prower accidentally stumbled upon Underzone after saving one of its inhabitants, Zeg. In order to keep the Zone's secret safe, the fox was not allowed to leave ever again. However, after saving the people from a poisonous gas leak, he was allowed to leave, providing he forget about everything he has seen.