The Eldorado Zone, originally referred to as the Diamond Mine Zone prior to its rebuilding, is a location that appears in the Sonic the Comic series published by Fleetway Editions. It is one of the Zones of Mobius, built after Doctor Robotnik's fall from power on the site of the old Diamond Mine Zone. The local residents all became rich because of the local diamond mine, and began to act like stuck-up snobs. They all wear lots of jewellery, primarily gold and diamond, and they only ever eat in expensive restaurants. The residents have more money than sense, and tend to waste their money on inadvisable investments or ridiculous fashions.
While flying through the Eldorado Zone, Tails decided to stop and see if he could get a veggie burger at a local chip shop, only to appalled at the resident's snobbish behavior. Nevertheless, he rescued the patrons of a local restaurant (Chez Pierre) from a runaway Drill-bot from the underground diamond mine, which had homed in on the jewellery of the diners and burst through the ground. One woman tried to give him a diamond necklace as a thank you, but Tails turned it down and was spurned for lack of class by the wealth-obsessed residents.
Soon afterwards, a diamond tiara was stolen from the apartment of Mrs. Curly-Smythe. A security camera shot showed a silhouetted figure, much like Tails, entering the thirteenth-floor apartment from the outside. The Zone's residents immediately assumed Tails was responsible, declaring him a thief. Even when Tails was present immediately after a robbery, while the real thief escaped, they accused him, but Tails finally convinced them to give him a chance to clear his name.
With the help of the local residents, Tails laid a trap for the thief by painting a bike frame and claiming it was the 'Golden Bike Frame of the Steptoe Zone'. This successfully drew out the thief, who called himself the Leaf and flew by means of a pair of mechanical wings. Tails chased him through the sky until the wings ran out of power, then handed him over to the authorities.
Some time later, a group of investors from the Eldorado Zone travelled to the Casino Night Zone, where Max Gamble tried to sell them his Metal Mate construction robot, which would have put the local builders out of business. The investors seemed interested until the robot short circuited and went haywire, after which they all ran away.
The residents of the Zone later became obsessed with the designs of fashion guru Velvet Smythe, who made money off them by creating crummy designs and selling them at a tidy profit. One such range was his "Badnik-chic" trend, in which people wore the remains of old Badniks as fashion accessories. Velvet lured a Badnik attack to the Zone in order to get more Badnik parts for his designs, only to be kidnapped by Badnik Squadron-Z and subsequently rescued by Tails. During the rescue, Smythe fell in a hedge and emerged a complete mess, with leaves in his hair and torn clothes. His fans immediately proclaimed this as "state-of-the-art retro-scruffy" and followed suit by ripping their own clothes and messing up their hair.
A chameleon thief named Loot the Treasure Seeker stole a valuable statue, the Bronze Monkey, from the Eldorado Zone's Museum of Arty Art. The curator called on Tails and private detective Harry Mole to investigate. During a second robbery at the same museum, in which Loot attempted to steal a statue called the Golden Handshake, Tails and Harry managed to apprehend Loot and recover both statues.
- The Eldorado Zone is named after El Dorado, a legendary city made of gold in South America.